In a tiny house, every drop of water matters. A DIY greywater system lets you reuse gently used water from sinks, showers, and laundry—reducing waste, conserving resources, and cutting utility costs. Whether you’re living off-grid or just want to live more sustainably, this guide walks you through how to build a simple, effective greywater system tailored for tiny homes.
🧠 What Is Greywater?
Greywater is wastewater from non-toilet sources like:
- Bathroom sinks
- Showers and tubs
- Washing machines
It does not include blackwater (from toilets or kitchen sinks with food waste), which requires separate treatment.
🌿 Why Use a Greywater System?
- Reduce water usage by up to 50% tinylair.com
- Irrigate gardens or flush toilets without using fresh water
- Lower utility bills and septic load
- Support off-grid or drought-resilient living
💡 Sustainability Tip: Always use biodegradable, plant-friendly soaps to protect soil and plants tinylair.com reerin.com.
🧰 What You’ll Need
- PVC or flexible drain pipe (1–1.5″)
- Diverter valve or 3-way valve
- Mesh filter or DIY gravel/sand filter
- Storage barrel or surge tank (optional)
- Hose or drip irrigation tubing
- Hose clamps, sealant, and fittings
🛠 Budget Tip: Simple gravity-fed systems can be built for under $100 tinylair.com.
🧭 Step-by-Step: How to Build a DIY Greywater System
1. 🚿 Identify Greywater Sources
- Bathroom sink
- Shower or tub
- Washing machine (avoid if using bleach or harsh detergents)
🔌 Note: Kitchen sinks are typically excluded due to grease and food particles.
2. 🔀 Install a Diverter Valve
- Place a 3-way valve on the drain line to switch between sewer/septic and greywater reuse.
- This allows flexibility during winter or when using non-plant-safe products.
🧠 Code Tip: Check local regulations—some areas require diverters or restrict greywater use tinylair.com The Tiny Life.
3. 🧼 Filter the Water
- Use a mesh screen or gravel/sand filter to remove hair, lint, and debris.
- For laundry greywater, add a lint trap to the hose.
🌱 Eco Tip: Filtering protects your soil and prevents clogs in irrigation lines.
4. 🛢 Add a Surge Tank (Optional)
- Collect greywater in a barrel or tank to regulate flow to your garden.
- Use gravity or a small pump to distribute water.
⚠️ Health Tip: Use greywater within 24 hours to avoid bacterial growth.
5. 🌻 Distribute to Plants or Toilets
- Use drip irrigation or perforated hose to water trees, shrubs, or ornamental plants.
- Avoid edible crops unless using subsurface irrigation.
🚽 Indoor Use: Greywater can be routed to flush toilets with additional plumbing and filtration.
📐 Sample Greywater Layout for a Tiny House
Shower → Diverter Valve → Mesh Filter → Surge Tank → Drip Irrigation
Or for ultra-simple setups:
Bathroom Sink → Hose → Garden Bucket (gravity-fed)
🧯 Safety and Maintenance Tips
- Clean filters weekly
- Flush system with clean water monthly
- Avoid storing greywater long-term
- Label all greywater lines clearly
- Use only greywater-safe soaps and detergents
🧪 Testing Tip: Monitor soil and plant health to ensure your system is working as intended.
🔗 Related Articles in the Plumbing & Water Systems Cluster
- Composting Toilet Installation Guide
- Rainwater Filtration for Tiny Homes
- Low-Flow Shower Options for Small Spaces
- Tiny House Plumbing Layout Ideas
Sources:
1. Tiny Lair – DIY Greywater Recycling System Guide
2. The Tiny Life – Simple Greywater Systems
3. Tiny Homes DIY – Greywater Systems Explained
4. Habitatista – 9 Ways to Integrate Greywater Systems
5. Reerin – Greywater Systems for Tiny Houses