💧 DIY Greywater System for Tiny Houses: Reuse Water and Reduce Waste

One surprising fact: a typical tiny house owner could save thousands of gallons a year by reusing sink and shower water, cutting outdoor water demand dramatically.

This article introduced a practical, low-cost approach that used common parts and gravity to irrigate fruit trees in dry yards. It described a proven settling tank feeding a surge tank that sent water to mulched driplines by gravity.

The design relied on biology and fluid dynamics rather than complex filters, with an annual siphon-pump cleanout through an inspection hatch. Simple components kept costs down and made the plan accessible to those living in small homes.

Readers would find two clear build paths: a settling-and-surge tank dripline fit for orchards and a compact barrel-based grey water septic with a short leach line for quick subsurface infiltration. Guidance covered sizing, slopes, pipe placement, plumbing integration, and maintenance to avoid surface seepage.

Key Takeaways

• Reuse of shower and sink water can cut outdoor water use by thousands of gallons annually.
• Settling tank → surge tank → mulched driplines is a field-tested, low-cost approach.
• Gravity and soil biology did most of the treatment; annual inspection kept performance high.
• Two build paths matched orchard irrigation or quick subsurface infiltration needs.
• Legal and safety basics were covered; toilets and some kitchen waste remained separate.
• Practical links and resources offered step-by-step plans and parts lists for U.S. owners: tiny house greywater guidance and step-by-step build notes.

DIY Greywater System For Tiny Houses

A compact, gravity-fed setup can turn bathroom outflow into steady irrigation without pumps.

The arrangement places a settling tank below the bathroom outflow. When the tank reaches about three-quarters full, overflow routes into a surge tank. The surge tank then feeds mulched driplines by gravity to irrigate fruit trees and garden beds.

This approach avoids complex filters and reduces turbulence, which helps solids settle. The surge tank evens out intermittent flows from showers or tubs, giving steady distribution through driplines.

Match the approach to your site: use the settling→surge→dripline way where orchards or beds exist. Choose a barrel-based leach option when quick subsurface infiltration is needed and irrigation areas are limited.

• Keep lines and tanks right-sized to prevent surface seepage in small yards.
• Keep discharge under mulch to reduce odors and animal contact while letting soil biology finish polishing the water.
• Minimal maintenance: annual inspections and cleanouts keep performance high.

Understanding Greywater, Blackwater, And Tiny House Plumbing Basics

Understanding which household flows are safe to reuse makes planning water reuse and drainage much easier.

What Counts As Greywater Versus Blackwater

Greywater typically includes water from bathroom sinks, shower drains, and washing machines. It has lower contamination than toilet outflow and can be routed for irrigation in many sites.

Black water includes toilet waste and, in some jurisdictions, kitchen and dishwasher effluent due to grease and food particles. Codes often treat kitchen discharge as black water because oils and food increase contamination risk and affect legal compliance.

How Tiny House Plumbing, Tanks, And Pumps Work

Compact house plumbing uses flexible pipes such as PEX or rigid PVC, small water heaters, and short drainage runs to save space. Pressure regulation is important when connecting to a city spigot or an RV park to protect fittings and fixtures.

Tanks for fresh water, greywater, and black water are common in mobile or off-grid setups. Pumps provide flow when gravity isn’t available.

• Keep greywater separate from black water to reduce health risks and ease irrigation reuse.
• Label and color-code pipes and valves to avoid cross-connections in tight spaces.
• Use accessible cleanouts and unions so maintenance fits within dense cabinetry.
• Choose low-flow showerheads and aerated faucets to reduce water volume and downstream load.

Plan space for future upgrades such as a filter, diverter, or an extra line if codes or needs change. For more layout ideas, see this plumbing layout guide.

Legal, Safety, And Health Considerations In The United States

Many U.S. jurisdictions encourage reuse of non-toilet flows, but rules and permits vary widely. Homeowners should confirm local setbacks, trench depths, and clearances before altering plumbing or landscaping.

Local Codes, Permits, And When Reuse Is Encouraged

Check permits early. Many local agencies allow single-family reuse for garden irrigation with specific requirements. Setbacks from wells, waterways, and property lines matter.

Keep greywater separate from black water and sewer lines. Document valve locations and cleanouts to help inspections and future maintenance.

For technical health references, consult public health guidance.

Safe Soaps, Food Particles, And Keeping Animals Away

Choose biodegradable, low-salt soaps to protect soil biology and plants. Avoid grease and food particles because many codes treat kitchen discharge as black water.

Keep outflows below mulch or soil to cut odors and deter pets and wildlife. Subsurface distribution also reduces aerosolization and human contact.

“Well-designed subsurface discharge minimizes health risks and keeps the landscape processing water safely.”

• Monitor for oversaturation and surface seepage after heavy washing or rain.
• Rotate zones and adjust flows seasonally to avoid compacted or saturated soil.
• Maintain clearances from drinking water lines and city connections to prevent cross-contamination.

Safe operation is ongoing: screen solids where permitted, verify allowable discharge areas, and keep animals away from distribution zones to protect people and plants.

Planning, Sizing, And Site Selection For Your System

A clear water budget makes choosing tanks, placement, and drainage much easier. Start by estimating daily volumes from showers, bathroom sinks, and laundry. Track one typical week and use the average to size storage and distribution.

Example: light-use layouts often used two 55-gallon barrels plus a 10′ leach line to handle roughly 75 gallons per day. Larger setups used an IBC settling tank with an inspection hatch that overflows at about three-quarters full into a surge tank, then gravity-feeds mulched driplines.

Estimating Daily Water Use And Tank Capacity

Sum typical fixture flows to pick a working tank capacity. Design with a safety margin for guests and added appliances. For light use, staged barrels buffer hits like a drained tub so the main pit does not back up.

• Buffer for surges: use a surge tank or staged barrels to prevent backups.
• Oversize modestly: add length to distribution lines to reduce wet spots over time.

Gravity, Slope, And Placement Relative To The House

Aim for about 1/4″ per foot slope from the house to the distribution area. Place settling tanks or barrels below the bathroom outflow to reduce head pressure and avoid pumps.

Site tip: locate a main pit roughly 7’×4’×5′ with 2′ of drainage gravel at the base when using larger buried tanks. Always include a visible, accessible overflow routed to a safe area.

Choosing Between Irrigation Dripline And Leach Line Infiltration

Pick mulched driplines when you want to irrigate fruit trees or garden beds. Choose a short leach line field when space is tight or subsurface infiltration is preferred.

Run a small test trench or percolation test to observe infiltration. Document elevations, slopes, and distances to plants to protect roots and guide future work.

“Designing with modest safety margins and clear elevations prevents wet spots and protects the house.”

For guidance on selecting a water tank and plumbing layout, see this tiny house water tank selection.

Materials, Tools, And Components Checklist

A clear parts list and simple tools cut build time and reduce surprises on site.

Basic items to gather before digging:

Settling Tank, Surge Tank, Dripline, And Mulch Materials

An IBC settling tank with an inspection hatch and a concrete surround makes the primary pit sturdy. A modified olive drum or small surge tank evens flow to driplines beneath mulch. Use dripline rated for wastewater distribution and compatible fittings to split flow around tree basins.

Barrels, PVC, Leach Line, Gravel, And Vapor Barriers

For the barrel approach, collect two 55-gallon plastic barrels, 3″ Schedule 40 PVC with 90° elbow and couplers, and threaded caps. Add a 4″ cleanout assembly with a footloose sewer cap.

Bring ~4 tons of drainage gravel, ~30 sq ft of vapor barrier, a 10′ perforated leach line, solvent cement, waterproof sealant, and hole saws (3.5″ and 1″).

• Layout aids: string lines, level, stakes, measuring tape.
• Tools/consumables: hole saws, sealant, solvent cement.
• Safety: gloves, eye protection, dust mask.

Tip: Assemble parts on a flat surface to confirm fit before excavation and mark cleanouts with a protective stone ring for service access.

How To Build A Settling Tank And Surge Tank Dripline System

Overview: Route bathroom and shower outflow into a below-grade settling pit, then overflow cleaner water into a nearby surge tank that feeds mulched driplines. This layout uses gravity and simple plumbing to deliver steady irrigation with minimal fuss.

Concept: Settling Then Surge To Mulched Driplines

Calm then pulse: Water first slows in a settling tank so solids drop out. When the pit reaches the set overflow, water travels to a surge tank that evens intermittent flows into the dripline.

Setting The Tank Below Bathroom Outflow

Place the main tank downslope from the house so gravity moves flows without a pump. This reduces moving parts and lowers maintenance needs.

Inlet, Outlet, And Overflow Pipe Placement For Better Settling

Fit a right-angle inlet to dissipate inflow energy. Set the overflow about three-quarters up the tank to draw clearer water that had more time to settle.

Installing The Surge Tank For Intermittent Flows

Locate the surge tank slightly lower than the overflow point so household bursts become measured pulses along the dripline. Include an inspection hatch for an annual siphon cleanout.

Laying Dripline Under Mulch In An Orchard Or Garden

Trench downslope from the surge tank and run dripline beneath at least 2–3 inches of mulch. Subsurface placement protects emitters, keeps odors down, and engages the soil food web to polish the flow.

Why No Filters: Letting Biology And Fluid Dynamics Work

Less clogging, less fuss. The design relies on settling and soil processing instead of fine filters. Add an emergency overflow from the settling tank to a safe area and document inlet/outlet heights, trench depth, and dripline length for future adjustments.

“Design the flow path so calmer water stays longer; biology and gravity will do most of the work.”

• Keep the cleanout accessible for yearly maintenance.
• Protect dripline under mulch to deter animals.
• Record elevations and lengths to simplify future upgrades.

How To Build A Barrel-Based Grey Water Septic With Leach Line

A pair of modified plastic barrels linked to a short leach line offers a simple path to treat and disperse household water.

System Layout And Slope From Source To Field

Siting began at least 20′ downslope from the house source with about a 1/4″ per foot fall. This keeps flow steady and avoids standing pockets.

Excavation Dimensions, Trenches, And Drainage Gravel

Dig a main pit roughly 7′ × 4′ × 5′ deep. Place about 2′ of drainage gravel on the base before setting barrels.

Preparing Barrels: Perforations, Couplers, And Connections

Turn two 55-gallon plastic barrels upside down. Drill at least twelve 1″ holes in each bottom. Cut opposing 3.5″ side holes to accept 3″ Schedule 40 PVC couplers.

Installing Leach Line, Vapor Barriers, And Cleanouts

Step barrel elevations slightly lower downstream and test-fit 3″ pipe with 90° bends as needed. Add about a foot of gravel in the trench and lay a 10′ perforated line with holes facing down.

Sealing, Backfilling, And Protecting Access Points

Cover pit gravel with vapor barrier, cut neatly around barrel tops, and place another barrier over the leach line. Install a 3″ threaded cap on one barrel and a 4″ footloose sewer cap on the other as cleanouts.

Seal every penetration with waterproof caulk before backfilling. Mark cleanouts with stones or edging for easy access.

Testing Flows And Avoiding Ground Oversaturation

Perform a live test by running sinks, shower, and washing machine flows and watching cleanouts. Look for rapid infiltration and no surface pooling.

If the soil shows slow percolation or seepage, extend the leach line or reduce inflow volume to prevent oversaturation.

For a detailed build reference and alternative layouts, see this water septic guide: water septic guide.

Plumbing Integration, Pumps, And Tanks For Tiny Houses

Start by mapping every drain and supply line so connections feed the intended storage and dispersal points.

Keep non-toilet flows separate. Connect sinks, shower drains, and the washing machine into a dedicated greywater branch that routes outdoors. Label each line and add a visible cleanout near the house exit. This reduces cross-connections and speeds service.

Connecting From Sinks, Showers, And Washing Machines

Use PEX or PVC to run compact runs from fixtures to the branch line. Install unions and shutoffs at the wall so technicians can isolate segments easily.

Avoid sharp bends that trap hair and soap scum. Map the path and slope pipes gently toward the outdoor tank or distribution point.

Pressure Regulation With RV Hookups And Grid Connections

Always fit a pressure regulator on RV or municipal hookups to protect fittings and faucets. A regulator prevents over-pressurizing small house plumbing and preserves fixture life.

Supply gear should include drinking water hoses, sewer hoses, and heated hoses where freezing is a concern. Label each connection and keep valves accessible.

Off-Grid Options: Water Storage, Solar Pumps, And Rainwater

Off-grid setups relied on freshwater tanks sized to occupants and trip length. Select a water tank that balances refill frequency with weight limits of the trailer or foundation.

Small pumps delivered pressure; a solar pump can sustain basic fixtures and reduce generator runtime. Rainwater collection filtered into tanks added a practical supply layer.

Tip: Low-flow fixtures cut demand and extend time between refills. Place accessible cleanouts and service unions at the house exit for quick seasonal switches.

“Label valves and lines to allow quick isolation when switching between hookup and off-grid modes.”

For a practical guide to plumbing layouts and parts lists, see this tiny house plumbing guide.

Maintenance, Health, And Troubleshooting Tips

Regular maintenance saves time and prevents small issues from becoming health hazards. A short annual inspection keeps sediment from building up and preserves steady water flow. The guidance below focuses on practical checks, odor control, and winter care so the greywater approach runs reliably.

Annual Inspections, Sediment Removal, And Cleanouts

Schedule one yearly service. Open inspection hatches and cleanouts, siphon or pump settled material, and confirm overflows and outlets are clear.

• Record the date and any volume estimates when removing sediment.
• Check barrel cleanouts and the inspection hatch after heavy use or laundry days.
• Verify there is no backflow toward the house or sewer connections.

Preventing Clogs, Odors, And Surface Seepage

Use hair traps at fixtures and ask occupants to avoid grease and harsh chemicals to protect soil biology.

• Scan mulched driplines and leach areas for wet spots or smells; these indicate oversaturation or clogging.
• Occasionally flush lines through cleanouts and confirm vapor barriers over gravel remain intact.
• If odors persist, extend distribution length or add a small branch to spread flow.

Seasonal Adjustments And Protecting Pipes From Freezing

Rotate zones and allow parts to rest during wet seasons to keep soils aerobic. Insulate or heat-trace near-house runs and keep distribution lines below frost depth.

• Monitor surge behavior after showers to avoid peaks that push water uphill.
• Document maintenance, observed flow rates, and any corrective actions taken.
• When opening cleanouts, wear gloves, keep pets away, and follow basic safety steps.

“Simple, scheduled checks and small corrective moves—extend lines, stagger loads, or add a distribution branch—solve most issues.”

Conclusion

Two clear, field-tested ways let small-house owners reuse non-toilet flows: a settling-and-surge approach to feed mulched driplines, or a compact barrel-and-leach design for subsurface infiltration.

Careful planning of tank placement, pipe elevations, and overflow paths keeps performance steady without complex pumps. Selecting the right water tank sizes, durable materials, and accessible cleanouts makes maintenance simple.

Subsurface delivery under mulch or into a leach line reduces odors and limits animal contact, while codes in many areas support single-family reuse when kitchen and black water are kept separate.

Next steps: verify local rules, finalize a materials list, and mark trenches and tank locations before digging. For a practical guide, see this grey water system guide.

FAQ

What is the difference between greywater and blackwater?

Greywater comes from showers, sinks, and laundry and contains soap, hair, and food particles. Blackwater includes toilet waste and requires septic or sewer treatment. Treating and reusing water from baths and sinks reduces discharge but never includes toilet waste.

Which fixtures should be routed into a reuse setup?

Shower drains, bathroom sinks, and washing machines are ideal sources because they produce mostly soapy water without sewage. Kitchen sinks often contain food grease and are best sent to the sewer or separate treatment unless robust pretreatment is used.

How large should tanks be based on daily water use?

Estimate daily volume by multiplying occupants by average per-person usage (showers, laundry, sinks). A small household often needs 50–150 gallons of combined holding capacity to balance flows and irrigation needs; designers size settling and surge tanks so intermittent surges don’t overwhelm driplines.

Can gravity feed be used, or is a pump required?

Gravity works when tanks sit higher than the landscape or irrigation zone and the site has sufficient slope. Pumps are needed when the house outlet is lower than the garden, when pressure is required for dripline, or for intermittent pressurization using a small 12V or AC pump.

Are filters required before sending water to mulched dripline?

Many low-tech designs use settling tanks and surge tanks instead of fine filters to allow solids to drop out and biological processes to stabilize water. Coarse screens help keep large debris out, but avoiding frequent clogging often means using pre-settling rather than delicate filtration.

How should inlet, outlet, and overflow lines be arranged in a settling tank?

Inlet should enter near the tank top and be directed to reduce turbulence. Outlet draws from mid-level to avoid surface scum and settled solids. An overflow line at the top sends excess to a secondary field or sewer to protect the tank from overfilling.

What materials are recommended for barrels, pipes, and driplines?

Food-grade polyethylene barrels, schedule 40 PVC for buried lines, and commercial micro‑drip tubing with pressure compensating emitters work well. Gravel for leach trenches, geotextile for separation, and heavy-duty mulch or wood chips protect surface driplines.

How steep should trenches and leach lines be placed?

Trenches typically follow gentle slopes; avoid steep drops that cause erosion. A slight grade helps flow without creating velocity that resuspends solids. Local practice often keeps trenches nearly level or with a very low gradient to maximize infiltration.

Are permits required and how do local codes affect reuse?

Regulations vary widely across U.S. jurisdictions. Many counties and states allow limited reuse with permits; some encourage irrigation reuse with restrictions. Always check local public health or building departments and obtain any required approvals before construction.

What soaps and detergents are safe to use?

Use biodegradable, low-sodium, and low-phosphate formulations that avoid antibacterial chemicals. Products labeled safe for septic systems, like certain Seventh Generation or Dr. Bronner options, are generally appropriate and protect soil biology used in treatment.

How can food particles and fats be managed?

Capture solids with strainers at drains, avoid sending kitchen sink water to reuse fields, and provide grease traps if kitchen discharge must be included. Regular removal of accumulated solids from settling tanks prevents odors and surface seepage.

What protection is needed to keep animals away from distribution areas?

Cover driplines with mulch, use fencing or plant thorny hedgerows, and bury distribution tubing slightly below the mulch layer. These steps reduce access and protect lines from damage and contamination by pets or wildlife.

How deep should buried barrels or tanks be placed relative to the outflow?

Tanks are typically placed below the bathroom outflow to allow gravity in. Depth depends on frost line, pump access, and maintenance needs; burying below frost depth in cold climates prevents freezing but should still allow cleanout access.

What are common troubleshooting steps for clogs and odors?

Inspect inlet screens and clean settling chambers regularly, remove accumulated sludge, flush lines with clean water, and check for leaks or infiltrating soil. Odors often indicate anaerobic pockets or solids buildup—removing sludge and restoring aerobic flow usually fixes the issue.

How often should tanks and driplines be inspected and serviced?

Annual inspections are standard, with sediment checks and cleanouts as needed. More frequent checks may be required in high-use situations. Cleanouts, pump maintenance, and emitter flushing help maintain reliable flow and prevent backups.

Can rainwater harvesting integrate with the reuse setup?

Yes. Rainwater can supplement irrigation storage or feed a surge tank after basic filtration. Careful separation of potable and nonpotable lines and adherence to cross-connection rules are essential when combining sources.

What off-grid options exist for pumping and power?

Solar-powered 12V pumps, battery-backed systems, and manual hand pumps provide off-grid pressurization. Low-power submersible pumps paired with pressure switches and small solar arrays often supply reliable intermittent irrigation.

How should systems be winterized in cold climates?

Drain aboveground lines, insulate or heat buried components to below-freeze depths, and protect pumps and tanks with frost-proof enclosures. Seasonal shutoff to the irrigation field and redirecting flow to sewer before freezing temperatures helps prevent damage.

What are best practices to avoid ground oversaturation?

Size infiltration areas correctly, use multiple distribution trenches, stagger irrigation timing, and monitor soil moisture. Excessive loading can cause surface seepage—spreading flows and using surge tanks prevents oversaturation.

Are there commercial resources or brands for tiny house plumbing and components?

Companies like Camco, SharkBite, and Rain Bird supply fittings, pumps, and dripline components used by small-home builders. For tanks and barrels, Norwesco and Snyder Industries offer polyethylene storage that fits small-scale reuse projects.nd plant health to ensure your system is working as intended.