For most community water systems use HDPE (black polyethylene) pipe for the main line from the source to the storage tank and PVC for the distribution runs from the tank to the standpipes, and keep bamboo for temporary lines, since it rots in 2-5 years. Choose a pipe whose pressure rating exceeds the line’s highest static pressure plus a surge allowance, and never use lead solder or pipe salvaged from unknown industrial service.
Part of Community Water System
Pipe material selection is the choice of what the buried water line is made of, weighed on pressure rating, durability, ease of joining, sunlight resistance and the safety of the water it carries.
The Joint, Not The Pipe, Is Usually What Fails
The comparison in the community water system page is the starting point.
| Material | Pros | Cons | Best for |
|---|---|---|---|
| HDPE (black poly) | Flexible, UV-resistant, joins with barbed fittings | Needs clamps, can kink | Main lines, buried runs |
| PVC | Cheap, rigid, solvent-welded joints are strong | Brittle in cold, degrades in sunlight above ground | Distribution networks |
| Bamboo | Free, abundant in the tropics | Rots in 2-5 years, leaks at joints | Temporary systems |
| Galvanized steel | Very strong, long-lasting | Heavy, expensive, rusts internally over decades | High-pressure sections |
Other materials that a rebuilding community can make are covered elsewhere: fired clay (Clay Pipes), bored logs (Wooden Pipes) and hand-formed iron (Metal Pipes). Pipe-making in general is in Pipe Making.
What You Need
- The highest static head on the line in meters, from the survey
- The route, noting where pipe will be exposed to sun, frost or traffic
- A list of available materials, with proof of what they carried before
- The right fittings and the tools to make joints: clamps and barbed fittings for HDPE, solvent cement for PVC
Method: Match The Material To The Run
Step 1: Rate the pressure. The pipe’s class is its nominal pressure in bar at 20 °C (Pipe Sizing). It must exceed static head ÷ 10, plus the surge from closing a tap quickly.
Step 2: Pick the material for each run. Long buried main: HDPE. Short distribution branches near the standpipes: PVC. Anything that must be above ground in the sun: HDPE, or bury it.
Step 3: Plan the joints. Each joint is a possible leak and a possible entry for contamination. Use as few as the route allows.
Step 4: Bury it. The carrier says to bury all pipes at least 30 cm deep to protect them from UV and physical damage. That depth does not protect against frost: where the ground freezes, bury below the frost line (Burial Depth).
Worked Example: Is A 10-Bar Pipe Enough?
A line has 60 m of static head, the ceiling in this wiki’s distribution rules.
- Static pressure: 60 m ÷ 10 = 6 bar.
- Surge: Isolation Valves gives about 3 bar for a fast valve closure.
- Peak: 6 + 3 = 9 bar. A 10-bar class pipe passes with 1 bar to spare; a 6-bar class pipe does not, even though it equals the static pressure.
The conclusion is to close valves slowly and to buy the class above the static figure, not equal to it.
Common Mistakes
- Using pipe because it is there. Pressure rating, bore and what it carried before all matter.
- Leaving PVC above ground. It degrades in sunlight and is brittle in cold.
- Skipping the clamp on a barbed fitting. The joint pulls off under pressure.
- Assuming a rating applies when hot. Ratings are quoted at 20 °C; plastic weakens as it warms, so a pipe in the sun carries less.
Safety
Lead, unknown pipe and a pressurised failure
Never use lead solder or lead pipe on a drinking-water line. Never use salvaged pipe that carried fuel, pesticides or industrial chemicals, because the walls hold them and release them into the water; use only pipe whose past is known. Pressurised pipe fails violently. Test with water after bleeding the air, never with compressed air, and keep clear of the line while it is first pressurised.