Yellow Water From Your Tank in Delhi? Causes & Fixes
Yellow, brown or rust-tinted water almost always has one of four causes. Here is how to tell which one you have.
Yellow water is the most common complaint we get in Delhi, and it is also the most misdiagnosed. Before you assume the tank is the problem, run one quick test.
The two-tap test
Fill a clear glass from a tap fed directly by the municipal line — usually a ground-floor kitchen tap that bypasses the tank. Fill a second glass from any tap fed by the overhead tank. Compare them against white paper.
- Only the tank tap is yellow → the tank or the pipe from it is the source
- Both are yellow → the supply itself is carrying sediment; the tank is collecting it, not creating it
- Yellow only for the first few seconds → deposits in the pipe run, not the tank
- Yellow clears when left standing → suspended sediment; if it does not clear, dissolved iron
The four causes
Iron and rust. Common on borewell supply in outer Delhi and in buildings with old GI pipework. Dissolved iron oxidises on contact with air, which is why the water is clear at the tap and yellow after standing.
Settled silt disturbed. A tank with years of accumulated sediment stays clear while the water is undisturbed and turns yellow every time the level drops enough to stir the base — typically in the evening after heavy use.
Tanker water. Summer tanker deliveries carry visible grit. It settles within hours, so the tank looks fine, then discolours whenever it is stirred.
Post-monsoon municipal turbidity. DJB supply turbidity spikes during and after heavy rain. This one resolves on its own; the tank problem it leaves behind does not.
What actually fixes it
If the source is the tank, cleaning fixes it — but only if the sludge is extracted rather than flushed into your outlet. A partial clean that pushes silt into the plumbing produces a week of clear water followed by exactly the same yellow.
If the source is a rusting GI pipe run, cleaning the tank will not help and no honest cleaner will tell you it will. That is a plumbing replacement.
If the source is supply-side, clean the tank quarterly instead of half-yearly so the sediment never builds up enough to be stirred.
Frequently Asked Questions
- Is yellow water dangerous to drink?
- Iron discolouration is mostly an aesthetic problem. Silt-driven yellowing is not — sediment carries bacterial load. Either way, do not drink it untreated while you find the source.
- Will an RO fix it?
- An RO protects your drinking glass, not your tank, your washing machine or your skin. It also clogs far faster on sediment-heavy feed water.
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