Silt, salinity & chemistry

Silt & abrasion

The waste valve and the check valve open and seat hundreds of times an hour, and the water that passes them does so at speed. Anything harder than the valve facings rides in that water as an abrasive. What matters is less the concentration than the particle size and hardness:

• Fine silt (below ~50 µm) — the cloudiness in glacier or monsoon water — passes through clearances harmlessly in modest amounts. Expect accelerated wear on rubbers, but seasons, not weeks, of service.
• Sand (50 µm – 2 mm) is the killer. It beds into rubber facings and laps them away, grinds swing-check pivots, and scours the drive pipe where velocity is highest. A sandy supply without settling works a ram to death in a single dry season.
• The defence is hydraulic, not heroic: a forebay that gives grit one quiet minute to settle (Intakes), an intake mouth off the bed, and if the source is chronically silty, a two-stage forebay with the first chamber flushable.

Debris & valve clearances

The clearances that make a ram work are the same ones that make it fussy. Typical numbers:

• Waste-valve seat and flap: anything larger than the seat gap — a leaf stem, a seed, a pine needle — prevents full closure. The symptom is a fluttery beat or none at all; the fix is a fine screen (1–2 mm mesh) upstream.
• Check valve: held open by debris, the pump beats but delivers nothing — the classic row in the troubleshooting matrix.
• Snifter orifice (~1 mm): clogs with anything fibrous; silently enlarges with grit. Its care is part of the monthly service.

Salinity, iron & pH

• Saline water pumps mechanically fine — the ram doesn't care — but demands corrosion-resistant materials throughout: brass, bronze, stainless and PE pipework, and an honest plan for what the waste stream does to the soils it crosses. Density slightly reduces the hammer per unit of velocity; nobody designs around it.
• Iron-bearing water stains everything and, where iron bacteria are present, grows slimes that foul the snifter and the check seat within months. Design access for cleaning, not just for rebuilding.
• Acidic water (low pH) eats galvanised and mild steel. Concrete-forebay water is also aggressive to unprotected steel. In either case, the drive pipe — the part that must be rigid — becomes the material puzzle; Pipe & Materials covers the stiff-but-corrosion-resistant options.
• Hard water leaves scale on seats and in the snifter hole where each beat dries a film. Occasional descaling belongs in the annual service.

Temperature

Water's viscosity falls as it warms, wave speeds shift slightly, and hot water dissolves air differently — all second-order effects. The honest limits are the practical ones: rubber facings age rapidly much above about 40–50 °C, and PVC pressure pipe loses rating steeply in warm water. Hot industrial effluent is the one water this page rules out without an engineered vessel and elastomer choice. At the other end, freezing is not a chemistry question but a design one — Cold-Climate Design.

The verdict table

Water that the machine can handle and that people can drink are two different questions — the second one is Water Quality & Potability.