Why did my pool turn brown or green right after filling it with borehole water?

The short answer

In most cases the cause is dissolved iron and manganese in the borehole water, which you cannot see in the fill water. Once the pool's water treatment goes in, the metals usually come out of solution and turn the water brown, yellow or green. They can also settle as stains on the finish, grout and fittings. Borehole water is also often acidic, which is hard on grout and cement-based finishes.

What to do now

• Stop topping up with the same untreated water.
• Avoid adding more and more treatment in the hope that it clears.
• Take photos of the water and any stains, and note when the colour changed.
• Have the source water tested, not just the pool water. We can order the test from an approved laboratory we work with.

What happens next

Next, ask us to inspect the finish. Where it is sound, our pool restart service can usually clean the pool in a way that suits the finish, refill it with suitable filtered or tested water and bring it back into service. Heavy staining means renovating the finish, which needs the pool drained. We discuss that with you first.

Reducing the risk next time

Incoming filtration on the pool fill and top-up lines removes iron and manganese before they reach the pool, provided it suits your water and is serviced. We design it from the results of the water test. The same plant can also supply the house. If the pool has a new cement-based finish, tell us before the first fill if the water comes from a borehole, lake or river.

What to send us for a first discussion

• Photos of the pool water, the stains and the pump room
• The property location and the approximate pool size
• Where the fill water came from, and any test results
• What you see now, and when it started