Water Distribution
Why This Matters
Having a water source is only half the problem. Getting that water reliably to where people live, cook, wash, and garden — without losing half of it to leaks and without contaminating it along the way — is the engineering challenge. A well-designed distribution network turns a water source into a water system.
Network Layout
Branched system: One main pipe from the source/tank, with smaller branches splitting off to each tap point. Simple, cheap, easy to understand. Downside: if the main breaks, everyone loses water.
Looped system: Pipes form a ring, so water can reach any tap from two directions. More pipe material needed, but if one section breaks, water still flows via the other path. Use this if you have the materials.
For a community of 5-30 people, a branched system is usually fine. Design it so you can add loops later as the settlement grows.
Pipe Sizing Guide
| Users Served | Minimum Pipe Diameter | Flow Capacity |
|---|---|---|
| 1-5 households | 25mm (1”) | ~0.5 L/sec |
| 5-15 households | 32mm (1.25”) | ~1 L/sec |
| 15-30 households | 50mm (2”) | ~2.5 L/sec |
| Main trunk line | 63-75mm (2.5-3”) | ~4-6 L/sec |
These assume gravity-fed systems with 10-30m of head. Larger pipes mean less friction loss and better pressure at distant taps. When in doubt, go one size up — you can never make a buried pipe bigger later.
Storage Tank Placement
The storage tank is the heart of the distribution system. It buffers the difference between source flow (constant, slow) and user demand (intermittent, peaked).
Elevation: The tank bottom must be at least 5m above the highest tap in the system to provide adequate pressure. Every 10m of elevation gives roughly 1 bar (14.5 psi).
Sizing: The tank should hold at least one full day’s water demand for the community. For 20 people at 50 L/day: 1,000L minimum. A 2,000-5,000L tank gives comfortable buffer.
Float valve: Install a float valve on the tank inlet (like a toilet cistern mechanism, but larger). When the tank is full, the float closes the inlet, preventing overflow. When users draw water and the level drops, the valve opens and the source refills the tank. This simple mechanism makes the whole system automatic.
Pressure Management
Too little pressure: taps barely dribble. Too much: joints blow, pipes burst, water is wasted.
Target range: 0.5 bar minimum (5m head) at each tap. Maximum 6 bar (60m head) in any pipe section.
Break pressure tanks: If your source is 80m above the community and your taps only need 10m of head, you need break pressure tanks to reduce the pressure. Place an open tank at an intermediate elevation. Water enters, pressure drops to zero, and a new pipe carries water down at manageable pressure.
Air valves: At every high point in the pipe route, install an air release valve (or just a tee with a short vertical pipe and cap). Trapped air blocks flow and causes water hammer.
Building Standpipes
A standpipe is a communal tap — a vertical pipe with a tap, set on a concrete pad.
Construction:
- Pour a concrete pad: 1.5m x 1.5m x 10cm thick, sloped 2% away from the tap on all sides
- Set a vertical galvanized or PVC pipe (50cm above the pad) in the concrete, connected to the distribution pipe below
- Install a ball valve or gate valve as the tap. Self-closing (spring-loaded) taps prevent waste but break more often
- Build a drainage channel from the pad edge to a soakaway pit (1m x 1m x 1m, filled with rocks)
Place standpipes within 200m of every household. One standpipe per 5-8 households is a good starting density.
Leak Detection
Every distribution system leaks. The question is how much.
Acceptable: <10% loss between source and taps Needs attention: 10-25% loss Critical: >25% loss — you’re wasting a quarter of your water
How to check: Measure flow at the tank outlet during a period when all taps are closed (late at night). If water is still flowing out of the tank, it’s going to leaks.
Finding leaks:
- Walk the entire pipe route looking for wet spots, green patches, or erosion
- In winter, look for spots where frost is melted above the pipe
- Close taps one section at a time — when the tank stops draining, the leak is in the last section you closed
Fixing leaks: For PVC — cut out the damaged section, install a repair coupling. For HDPE — use compression fittings or barbed repair couplers. Always carry spare fittings and a pipe cutter.
Winterization
In freezing climates:
- Bury all pipes below the frost line (depth varies: 0.5m in mild areas, 1.5m+ in severe cold)
- Install drain valves at every low point so you can empty exposed sections
- Insulate above-ground tanks with straw bales, earth, or foam
- If a section will freeze regardless, install a drain and shut it down for winter. Better to lose one tap than the whole system
Tip
A dripping tap won’t freeze (moving water resists freezing). In an emergency, leave the most vulnerable tap slightly open overnight. But this is a stopgap, not a design strategy.
Common Mistakes
| Mistake | Consequence | Prevention |
|---|---|---|
| Pipes too small | Poor pressure, long fill times, complaints | Size up, not down — always |
| No isolation valves | One repair means shutting off everyone | Install valves at every branch point |
| Tank too low | No pressure at taps | Tank bottom 5m+ above highest tap |
| No drainage at standpipes | Mud, mosquitoes, contamination | Concrete pad + drainage + soakaway |
| No air release at high points | Airlocks block flow | Tee + vertical pipe + cap at every summit |
What’s Next
- Community Water Testing — verifying your distributed water is safe
- Water Treatment at Scale — treating water before distribution
- Flood Control and Drainage — managing the water you don’t want