Transforming your laundry room into a water conservation powerhouse isn’t just about buying an Energy Star label—it’s about understanding the intricate dance between appliance engineering and ecological responsibility. Every year, the average household sends thousands of gallons of lightly used wash water down the drain, water that could be nurturing your fruit trees, hydrating your vegetable garden, or sustaining your native landscaping through dry spells. The right washing machine becomes the cornerstone of a sophisticated greywater recycling system, but only if you know exactly what specifications, features, and design elements to demand.
Hooking up a washer for garden irrigation represents one of the most impactful residential water-saving strategies available today, yet it’s shrouded in confusion about compatibility, detergent chemistry, and regulatory red tape. This guide dismantles the complexity, empowering you to evaluate any Energy Star washing machine through the lens of greywater safety, long-term soil health, and practical system design. Whether you’re planning a simple laundry-to-landscape setup or an integrated whole-yard system, these insights will ensure your investment works in harmony with both your household needs and your garden’s delicate ecosystem.
Best 10 Greywater-Safe Energy Star Washers for Garden Irrigation
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Understanding Greywater and Your Washer’s Role
What Qualifies as Greywater from Laundry?
Greywater is defined as any household wastewater that hasn’t come into contact with toilet waste, but not all laundry water is created equal. What flows from your washing machine falls into a unique category: it contains dirt, skin cells, food particles, and cleaning agents, but with the right system design, it’s perfectly suited for subsurface irrigation. The key distinction lies in contamination level—laundry greywater is generally considered “light” greywater, unlike kitchen sink water which carries heavy grease and bacterial loads.
Your washer’s design directly influences the quality of greywater produced. Machines with thorough rinse cycles dilute detergent residues more effectively, while those with specialized allergen cycles can actually produce cleaner greywater than standard cycles. The water’s temperature, pH, and chemical load vary dramatically between loads, making your machine’s flexibility a critical factor in system success.
The Ecological Win-Win of Reuse
Diverting laundry water to your garden creates a closed-loop system that benefits both your water bill and local watershed health. Most households generate 15-40 gallons per load, and with 300-400 loads annually, you’re looking at 4,500-16,000 gallons of water that could bypass the sewer system entirely. This isn’t just about conservation—it’s about reducing the energy and chemicals used in wastewater treatment plants while building drought resilience into your landscape.
The nutrient profile of laundry greywater, when properly managed, can actually enhance soil biology. Trace amounts of nitrogen and phosphorus from skin cells and organic debris feed beneficial soil microbes, while the water itself supports mycorrhizal networks that help plants access nutrients. The trick is preventing the harmful buildup of salts, surfactants, and synthetic compounds that can destroy this delicate balance.
Energy Star Certification Explained for Greywater Users
Water Efficiency Metrics That Matter
Energy Star certification for washing machines centers on two key metrics: Modified Energy Factor (MEF) and Water Factor (WF). For greywater systems, the Water Factor is your primary concern—it measures gallons used per cubic foot of capacity. A lower WF means less water per load, but this presents a paradox: ultra-efficient machines may concentrate detergents more heavily, potentially creating greywater that’s harsher on your soil.
The most greywater-friendly Energy Star washers typically have a WF between 3.0 and 4.0, balancing water conservation with adequate dilution. Machines scoring below 3.0 often use such minimal water that even greywater-safe detergents may not rinse thoroughly enough, leaving problematic residues on clothes and in the water destined for your garden.
Why Energy Star is a Baseline, Not a Guarantee
While Energy Star certification ensures basic efficiency standards, it doesn’t address greywater-specific concerns like drain pump durability, cycle customization, or chemical residue management. Many high-efficiency machines use proprietary wash motions and precise water metering that can complicate greywater diversion. The certification tells you nothing about whether a washer’s control board can handle being paused mid-cycle or whether its drain hose configuration is compatible with outdoor diversion.
Think of Energy Star as your starting point for efficiency, but you’ll need to dig deeper into technical specifications to assess true greywater compatibility. The most suitable machines often sit in the middle of the efficiency spectrum—efficient enough to save water, but robust enough to handle the demands of a diversion system.
Critical Features of Greywater-Compatible Washers
Manual Water Level Control vs. Automatic Sensing
Automatic load-sensing technology, while convenient for efficiency, can be problematic for greywater systems. These machines calculate precise water needs based on load weight, often resulting in unpredictable water volumes that make irrigation planning difficult. More critically, some sensors recalibrate mid-cycle if they detect imbalance, potentially disrupting your diversion setup.
Washers offering manual water level selection give you predictable output—crucial for sizing surge tanks and distribution lines. Look for machines with explicit “Small,” “Medium,” and “Large” settings rather than vague “eco” or “auto” options. This control allows you to match water output to garden needs; for instance, running a small load when only a few fruit trees need watering during dry spells.
Detergent Dispenser Design and Residue Issues
The dispenser drawer design significantly impacts greywater quality. Machines with single-dose, high-efficiency dispensers that fully flush detergent during the wash cycle produce cleaner greywater than those with built-in softener or bleach compartments that may retain chemicals. Look for drawers that are completely removable for manual cleaning—residual detergent buildup in dispenser crevices can contaminate otherwise clean rinse water.
Top-loading machines with central agitator columns often have simpler dispenser systems that rinse more thoroughly than front-loaders with complex multi-compartment drawers. However, this must be balanced against the fact that modern front-loaders typically use less water overall, creating a trade-off between dispenser cleanliness and water volume.
Drum Materials and Microplastic Concerns
Stainless steel drums are non-negotiable for greywater systems. Porcelain-coated drums can chip over time, releasing harmful minerals and creating sharp edges that damage fabrics, increasing microfiber shedding. While all washing machines contribute to microplastic pollution, machines with smooth, high-quality stainless drums and gentler wash motions minimize fiber breakdown.
Some advanced machines now feature specialized filters or wash motions claiming to reduce microfiber release. While these technologies are still evolving, any feature that reduces plastic particle pollution benefits your soil’s long-term health. Avoid machines with internal plastic heating elements or inferior plastic components that could leach chemicals into wash water over time.
Cycle Temperature Options and Their Impact
Greywater safety correlates strongly with wash temperature. Hot water dissolves more detergent chemicals and opens fabric fibers, releasing more dyes and residues into the water. Machines that offer true cold-water washing with effective cleaning performance produce the safest greywater. Look for models with dedicated cold-water cycles that don’t automatically add warm water to “assist” cleaning.
Conversely, the ability to occasionally run hot sanitizing cycles is valuable for system maintenance. Once monthly, a hot water wash with vinegar can flush your machine’s internal hoses and pump, preventing biofilm buildup that could clog your garden irrigation lines. The ideal machine offers both excellent cold-water performance and accessible hot-water options for maintenance.
Planning Your Garden Irrigation Hookup
Gravity-Fed Systems: What Your Washer Must Support
Gravity-fed greywater systems are simplest, requiring no pumps and minimal maintenance. For this approach, your washer’s drain pump must be powerful enough to push water vertically at least 6-8 feet to clear a wall penetration, yet not so powerful that it sprays water violently into your surge tank. The drain cycle’s flow rate—typically 5-15 gallons per minute—must match your distribution plumbing’s capacity to prevent backups.
Check the washer’s specifications for “drain height maximum.” Most can handle 8 feet, but some high-efficiency models have lower limits. The drain hose should be easily detachable from the standpipe without special tools, allowing quick switching between sewer and greywater diversion. Machines with permanent drain hose connections or proprietary fittings create installation headaches.
Pump-Assisted Setups: Power and Placement Considerations
If your garden sits uphill from your laundry room, you’ll need a pumped system. Some advanced washers offer integrated drain pumps with external switch controls, but most require a separate lift pump. The critical specification here is whether the machine’s control system can accommodate an external pump’s electrical load and automatic switching.
Look for washers with drain cycles that run a consistent duration rather than smart-sensing completion. This predictability allows your external pump controller to activate reliably. Machines that pause frequently during draining or have variable cycle lengths based on load type can cause premature pump burnout or incomplete water transfer.
Drain Height and Location: The Practical Details
The physical location of the drain outlet on the washer affects installation complexity. Machines with rear-mounted drains at mid-height offer easier access than those with low-profile bottom drains that require crawling behind the unit. Side-mounted drains provide the best accessibility for custom greywater plumbing.
Consider the drain hose diameter—standard 1-inch hoses are easiest to adapt to greywater systems. Some ultra-efficient machines use smaller diameter hoses that increase velocity but clog more easily and require specialized adapters. The hose material matters too; reinforced rubber hoses withstand outdoor temperature fluctuations better than thin-walled plastic that becomes brittle in sunlight.
The Detergent Dilemma: Choosing True Greywater-Safe Products
The “Biodegradable” Myth
“Biodegradable” on a detergent label means nothing for greywater safety. All detergents biodegrade eventually—the question is what they leave behind during decomposition. Many biodegradable formulas contain sodium salts, optical brighteners, and synthetic fragrances that persist in soil, accumulating to toxic levels over time. These chemicals don’t harm municipal wastewater systems but can devastate soil structure and microbial life.
True greywater-safe detergents are specifically formulated to be “biocompatible,” meaning they break down into elements that plants and soil microbes can actually use or tolerate. Look for third-party certifications like Greywater Action’s approval list or OMRI (Organic Materials Review Institute) listing, not just vague environmental claims.
Surfactants, Salts, and Buildup Chemistry
The primary danger in laundry greywater is sodium accumulation. Sodium-based surfactants and fillers (like sodium lauryl sulfate and sodium carbonate) destroy soil structure by dispersing clay particles, creating hardpan that repels water and suffocates roots. Potassium-based alternatives are safer but harder to find.
Phosphates, while banned in many laundry detergents, still appear in some “eco” formulas and cause rapid algae growth in soil, disrupting nutrient balance. Boron, found in some oxygen bleaches, is lethal to many plants at concentrations as low as 1 ppm. Your washer’s rinse efficiency directly affects how much of these chemicals remain in the greywater—a machine that leaves detergent residue on clothes is leaving it in your water too.
Creating a DIY Detergent Checklist
Before using any detergent in a greywater system, verify it meets these criteria: liquid form (powders contain more fillers), plant-based surfactants (coconut or corn-derived), no sodium salts listed in the first five ingredients, neutral pH, and zero synthetic fragrance or dye. Test any new detergent by watering a single plant for two weeks before full system deployment.
Your washer’s dispenser must be cleaned monthly when switching detergents to prevent chemical cross-contamination. Residual conventional detergent clinging to dispenser walls can contaminate dozens of greywater loads, so run a hot water cleaning cycle with vinegar between detergent types.
Protecting Your Soil and Plants
Managing Sodium Adsorption Ratio (SAR)
The Sodium Adsorption Ratio is the critical measurement determining whether your greywater will harm soil structure. It compares sodium concentration to calcium and magnesium levels. Laundry greywater typically has high SAR due to detergent salts, which is why direct soil application without mitigation is dangerous.
Your washer influences SAR through water volume—more dilution lowers the ratio. Machines with extra rinse options allow you to intentionally over-rinse loads destined for greywater diversion, significantly reducing SAR. Some greywater enthusiasts run a “dummy load” with just water after heavily soiled washes to flush the system before irrigating sensitive plants.
pH Fluctuations and Buffering Strategies
Laundry water pH typically ranges from 8.5 to 10 due to detergent alkalinity, far above the ideal 6.0-7.5 range for most garden soils. Repeated application can shift soil pH, locking up nutrients like iron and manganese. Your washer’s ability to run acidic rinse cycles (by adding vinegar to the fabric softener compartment) provides a simple buffering solution.
Machines with precise temperature control allow you to use cooler water, which carries less dissolved detergent and thus lower pH. The rinse water from the second rinse cycle is always safer than first-rinse water, so systems that capture only the final rinse provide better protection, though this requires more complex plumbing.
Best Plant Choices for Laundry Greywater
Not all plants respond equally to greywater irrigation. Fruit trees, ornamental shrubs, and mature perennials with deep root systems tolerate greywater best, as they’re less affected by surface salt buildup. Annual vegetables, especially leafy greens and root crops, are most sensitive and should only receive greywater during establishment phases.
Your washer’s cycle selection can tailor water quality to plant needs. Delicate cycles with minimal detergent work best for irrigation zones near sensitive crops, while heavy-duty wash water should be directed to trees and shrubs. Machines offering multiple cycle types give you this flexibility, effectively letting you “prescribe” different water qualities to different garden zones.
Navigating Legal Requirements and Building Codes
Permit Requirements by Region
Greywater legality varies dramatically by jurisdiction. Some states, like Arizona and California, have progressive codes explicitly allowing laundry-to-landscape systems without permits. Others require full engineering plans and inspections. Your washer installation must comply with local plumbing codes, which often mandate three-way diverter valves for easy sewer switching during rainy periods.
Document your washer’s specifications for permit applications—drain flow rate, water factor, and installation manual details help officials understand your system’s capacity. Some jurisdictions restrict greywater use based on machine type, prohibiting systems fed by commercial-grade or high-capacity washers in residential zones.
Why “Legal” Doesn’t Always Mean “Safe”
Building codes establish minimum safety standards, not optimal ecological practices. A system can pass inspection yet still damage soil over time if your washer produces overly alkaline water or you use marginally acceptable detergents. Code compliance focuses on preventing cross-contamination and nuisance conditions, not long-term agronomic health.
This gap means you must exceed code requirements for truly sustainable operation. Install a system that meets legal standards, then optimize washer settings, detergent choice, and irrigation scheduling based on soil testing and plant performance. Your goal is a system that’s both permitted and perpetually productive.
Designing a Resilient Greywater System
Essential Filtration Stages
Even the cleanest washing machine water needs filtration before garden application. Lint, hair, and soap scum will clog irrigation emitters within weeks. The first stage is a simple mesh filter bag attached directly to your washer’s drain hose—this catches the bulk of solids and is easily cleaned after each load.
Second-stage filtration involves a multi-layer filter box before your surge tank: course gravel, landscape fabric, then fine sand. Your washer’s drain pressure must be gentle enough not to blast through these layers. Machines with adjustable drain speeds or slower flow rates perform better here, giving filtration media time to work without channeling.
Surge Tank and Distribution Basics
Your washer’s output isn’t steady—it’s a surge of 15-25 gallons in 2-3 minutes. A surge tank (typically 30-50 gallons) smooths this flow into a steady trickle for irrigation. The tank must be sized to handle your machine’s maximum load volume plus 20% for safety. Energy Star washers with larger capacities (4.5+ cubic feet) may require bigger surge tanks to prevent overflow during back-to-back loads.
The tank’s inlet placement should be 6-8 inches below the washer’s drain outlet to prevent siphoning. Machines with top-mounted drain pumps provide better head pressure for this setup than those with low-mounted pumps that struggle with vertical lifts.
Mulch Basins and Infiltration Design
Subsurface irrigation through mulch basins is the gold standard for greywater safety. Basins—shallow depressions filled with wood chips around plants—filter water further and prevent surface contact. Your washer’s output determines basin size: each load should fill but not overflow its designated basin.
For clay soils, basins need to be larger (3-4 feet diameter) to prevent ponding. Sandy soils allow smaller basins with more frequent irrigation. Machines with precise volume control let you match output to soil infiltration rates, preventing the anaerobic conditions that create foul odors and attract pests.
Installation Best Practices
Access Panels and Future-Proofing
Install your washer with a removable access panel behind it, not a permanent wall enclosure. Greywater systems require periodic inspection of hose connections, diverter valves, and pump wiring. A 24x36 inch framed panel with drywall screws provides easy access without tools.
Route your drain hose through a PVC pipe sleeve in the wall, not directly through a rough hole. This allows easy hose replacement when it inevitably degrades from detergent exposure. Choose a washer with a standard hose connection—proprietary fittings make emergency replacements impossible.
Backflow Prevention Essentials
Building codes universally require an air gap between washer drain and greywater system to prevent backflow contamination. This means your washer’s drain hose must terminate 2 inches above the flood rim of your surge tank or diverter valve. The drain hose should be securely fastened but not airtight—clamp it loosely to allow air break if a backup occurs.
Your washer’s drain cycle creates negative pressure that can siphon water back from the greywater system. Install a vacuum break valve on the drain line, positioned higher than the washer’s water level. Some advanced washers have built-in anti-siphon features, but external protection is still required by code.
Winterization Strategies
In freezing climates, your greywater system must be drainable. Install shutoff valves and low-point drains on all outdoor lines. Your washer should be located on an interior wall, not in an unheated garage, to prevent internal freezing. Machines with automatic drain cycles that empty internal hoses after each use provide extra freeze protection.
Before first frost, run your washer on a clean-out cycle with RV antifreeze (propylene glycol, safe for greywater) to protect the pump and internal lines. Disconnect outdoor hoses and blow out lines with compressed air. Mark your washer’s manual with seasonal maintenance notes so you don’t forget these critical steps.
Maintenance Protocols for Long-Term Success
Monthly Cleaning Protocols
Your washer needs monthly maintenance to prevent greywater system contamination. Run an empty hot water cycle with 2 cups of white vinegar to dissolve detergent buildup in hoses and pumps. Clean the detergent dispenser drawer thoroughly—pull it completely out and scrub with an old toothbrush.
Inspect the drain pump filter (if accessible) for lint and debris. Even “self-cleaning” pumps accumulate material that can clog irrigation lines. Wipe the door seal with a vinegar solution to prevent mold, which can introduce pathogens into your greywater. These simple steps take 15 minutes but prevent expensive system failures.
Identifying and Fixing Common Clogs
The first sign of a clog is slow draining or water backing up into the washer. Check the inline lint filter bag—90% of clogs occur here. If clear, inspect the diverter valve for mineral buildup; soak it in vinegar if sticky. Persistent clogs in the machine itself indicate detergent residue; run multiple hot water cycles to clear.
Greywater-specific clogs often appear as reduced irrigation flow. Flush distribution lines monthly by switching the diverter to sewer and running a hot water cycle with vinegar. This backward flush clears biological growth and soap scum. If your washer has a “clean washer” cycle, use it weekly in greywater systems to prevent internal buildup.
When to Flush the System
Completely flush your greywater system if you notice: persistent soil surface crusting, plant leaf burn, or foul odors from mulch basins. Switch the diverter to sewer for two weeks, allowing rain or fresh water to leach accumulated salts from the soil. During this period, deep water your garden with fresh water to push salts below the root zone.
Your washer’s role in flushing is running hot water cycles without detergent to clean internal components. After the two-week flush, restart greywater use with half-strength detergent for a month, then return to normal. This seasonal “reset” prevents the slow degradation that ruins most greywater gardens within 3-5 years.
Cost-Benefit Analysis Realities
Upfront Investment vs. Long-Term Savings
A greywater-ready washer costs $200-400 more than a basic model when you factor in required features like manual controls and quality construction. Installation adds $300-800 for diverter valves, surge tank, and irrigation lines. However, at $0.01-0.02 per gallon for municipal water, a typical household saves $50-150 annually.
The real ROI comes during drought restrictions when your garden continues thriving while neighbors’ lawns brown. Property value increases of 2-3% are documented for homes with functional greywater systems. Your washer’s efficiency determines savings magnitude—machines using 15 gallons per load produce less valuable greywater than those using 25 gallons, but also cost less to operate.
Hidden Costs Most People Miss
Detergent costs double for greywater-safe brands—budget $0.30 per load versus $0.15 for conventional. Filter replacement bags cost $5 monthly. Annual soil testing ($50) is essential to monitor salt buildup. These ongoing expenses often exceed water savings, making greywater a lifestyle choice rather than pure economic decision.
Your washer’s durability affects long-term costs. Machines with easily replaceable drain pumps and standard hoses cost less to maintain. Proprietary parts can turn a $20 hose replacement into a $150 service call. Factor in a 10-year lifecycle when calculating true costs, and choose washers with robust parts availability and online repair guides.
Debunking Greywater Myths
The “Set It and Forget It” Fallacy
The most dangerous myth is that greywater systems run themselves. In reality, they require weekly monitoring: checking filters, observing plant health, adjusting diverter valves seasonally. Your washer’s performance changes over time—pumps weaken, hoses clog, sensors drift—requiring recalibration of your entire system.
Expect to spend 30 minutes weekly on system management. Forget one month of filter cleaning and you’ll spend three hours unclogging lines. Your washer’s manual holds clues about maintenance schedules; adapt these for greywater use, doubling cleaning frequency. Successful greywater gardeners treat their washer as a precision tool requiring constant attention, not an appliance to be ignored.
Why All Energy Star Washers Aren’t Automatically Safe
Energy Star measures energy and water consumption, not chemical output or ecological compatibility. A washer could score perfect Energy Star ratings while using a proprietary detergent system that leaves toxic residues. Some high-efficiency machines are so water-stingy they can’t properly rinse greywater-safe detergents, creating concentrated chemical water that’s worse than conventional machines using more water.
The certification also ignores material safety. A washer might have plastic drums that leach endocrine disruptors or hoses that degrade, releasing phthalates into your garden. Always verify drum material, hose composition, and detergent compatibility beyond the Energy Star label. The most greywater-safe machines often aren’t the most efficient—they’re the most thoughtfully designed for ecological cycles.
Frequently Asked Questions
1. Can I convert my existing Energy Star washer to be greywater-safe?
It depends on the model’s features. If your washer has manual water level controls, accessible drain hose, and stainless steel drum, conversion is feasible. However, machines with sealed drain systems, automatic-only controls, or plastic drums aren’t worth modifying. Check your manual for drain height specifications and whether the pump can handle external diversion.
2. How do I know if my detergent is truly safe for greywater irrigation?
Look beyond “biodegradable” claims. True greywater-safe detergents list potassium-based surfactants, have neutral pH (6-8), contain no sodium salts, boron, or chlorine bleach, and are liquid (not powder). Test by mixing 1 tablespoon in a gallon of water and measuring pH; it should read below 8.5. Reputable brands often display Greywater Action certification or OMRI listing.
3. Will greywater from my washer harm my septic system if I use a diverter valve?
No—a properly installed three-way diverter valve isolates greywater from your septic completely. The danger comes from improper installation where backflow could occur. Always maintain an air gap and install a vacuum break valve. During diverter switching, run a clean water cycle to flush any cross-contamination. Your septic system remains unaffected as long as the diverter is code-compliant.
4. What’s the minimum yard size needed for a washer greywater system?
You can utilize greywater effectively in yards as small as 500 square feet by targeting 2-3 fruit trees or large shrubs with mulch basins. The key is matching your washer’s output to plant water needs. A small yard requires more precise management—avoid overloading by switching to sewer during rainy periods. Even apartment balconies can use greywater with compact surge tanks and container plants.
5. Do I need a permit for a laundry-to-landscape system?
Permit requirements vary widely. California, Arizona, and Texas often allow laundry systems without permits if they follow health department guidelines. Most other states require plumbing permits for the diverter valve. Always check local building codes; even “permit-free” states require code compliance. Unpermitted systems can cause home sale complications and insurance issues.
6. How often should I clean the lint filter on a greywater washer system?
Clean the inline lint filter bag after every 3-5 loads, or weekly minimum. A clogged filter restricts flow, forcing the washer pump to work harder and potentially burn out. It also causes greywater to back up into the machine, creating odors. Keep spare filter bags on hand; they tear frequently. The 5-minute cleaning task prevents 3-hour clog-clearing sessions later.
7. Can I use greywater on my vegetable garden?
Only with strict precautions. Direct greywater application is safe for fruit trees and woody perennials, but root crops and leafy greens risk contamination. If you must water vegetables, use subsurface drip irrigation at least 6 inches deep, only apply to established plants (not seedlings), and stop greywater 30 days before harvest. Better yet, use greywater for fruit trees and save fresh water for vegetables.
8. Why does my greywater system smell bad?
Foul odors indicate anaerobic conditions from water pooling. Check for clogged distribution lines, oversaturated mulch basins, or insufficient infiltration. Your washer may be producing too much water for your soil type—switch to smaller loads or divert every other load to sewer. Add a tablespoon of vinegar to the rinse cycle to lower pH and discourage bacterial growth. Persistent smells require system flushing with fresh water.
9. Will using greywater void my washing machine warranty?
No major manufacturer explicitly voids warranties for greywater diversion, but damage caused by improper installation isn’t covered. If your pump fails due to back pressure from a clogged greywater line, that’s on you. Keep detailed installation photos and maintain the washer per manufacturer specs. Some extended warranty companies exclude “non-standard installations,” so read fine print before purchasing coverage.
10. How long do greywater-safe washing machines typically last in these systems?
With proper maintenance, expect 10-12 years—similar to conventional use. However, greywater systems place extra stress on drain pumps from lint and running more frequent cycles. Machines with accessible, replaceable pumps often last longer because you can service them. The outdoor plumbing components (hoses, valves) need replacement every 3-5 years due to UV and chemical exposure. Budget for a new washer pump around year 7-8, costing $150-300 in parts.