Private water supplies: the basics

If your water comes from a borehole, well or spring rather than the mains, you are responsible for its quality. That sounds daunting, but in practice it comes down to a simple routine: test regularly, and act on what you find.

Why private supplies need testing

Mains water is treated and monitored before it reaches you. A private supply is raw groundwater or surface water, and its quality changes with the seasons — heavy rain, ground works, farming activity and even a dead branch in a spring chamber can all affect it. Water that looks and tastes fine can still carry bacteria you cannot see.

What to test for

• Bacteria — coliforms and E. coli are the clearest sign that contamination is reaching your supply. This is the test to run first and most often.
• Metals — lead and other metals can come from the ground or from older pipework.
• Chemistry — nitrate, pH, hardness and similar parameters tell you how the supply behaves and what treatment suits it.

How often

A sensible rhythm for most households: a bacteria check after events that could disturb the supply — flooding, ground works, a change in taste or colour — and a fuller annual test covering bacteria, metals and chemistry once a year.

If something is raised

Do not panic — most problems have well-established fixes, from UV treatment for bacteria to targeted filtration for metals or nitrate. The key is knowing exactly what you are treating, which is what the test gives you.