Why your tap water tastes like a swimming pool

That faint swimming-pool taste is chlorine, and it is actually a sign your water is being looked after. Here is why it is there, why it lingers, and how a simple carbon filter removes it at the tap.

4 min read

First, the good news: that chlorine is there on purpose

Before water leaves the municipal treatment works, a small, carefully measured dose of chlorine is added to it. Its job is to kill germs — not just at the works, but all the way along the kilometres of pipes between the reservoir and your kitchen. Chlorinating drinking water is one of the great public-health successes of the last century, and it is the reason you can pour a glass straight from a municipal tap without a second thought.

Here is the part most people don't know: the dose is deliberately set so that a little chlorine is still left in the water when it reaches your home. That leftover chlorine — engineers call it a residual — is proof the protection is still working right up to your tap. No chlorine at the tap would actually be the worrying sign.

So if your water smells faintly of a swimming pool, nothing is broken. Your municipality is doing its job. The chlorine has simply finished its work by the time it reaches you — and now it is just a taste and smell you would rather not have in your tea.

So why does it taste and smell like a pool?

Chlorine belongs to the same chemical family as pool sanitiser, and the human nose is remarkably good at picking it up — even in tiny amounts. Some people barely notice it; others can taste it in their morning coffee. The strength can also vary from day to day and season to season, depending on how much chlorine was dosed and how far the water has travelled to reach you.

There is a second character in this story: chloramine. Some water supplies combine chlorine with a small amount of ammonia, creating a longer-lasting disinfectant called chloramine. From the municipality's point of view this is a feature — it keeps protecting the water further down the line. From your kitchen's point of view, it is more stubborn.

That stubbornness explains a common frustration. Plain chlorine slowly escapes from a jug of water left standing overnight, which is why your gran's fridge-jug trick sometimes works. Chloramine, on the other hand, mostly stays put. If letting your water stand doesn't improve the taste, chloramine is a likely reason — and it is a job for a proper filter.

How activated carbon takes it out (in plain words)

The tool for this job is activated carbon — essentially charcoal that has been specially treated until it is riddled with microscopic tunnels and pockets. All those tiny surfaces act a bit like Velcro for chlorine: as water flows through, the chlorine and the other compounds that cause off-tastes and odours stick to the carbon and stay behind, while the water carries on to your glass.

Carbon comes in two forms, and the names are simpler than they sound. Granular activated carbon — GAC — is loose granules, a bit like coarsely ground coffee packed into a cartridge. Water flows through it easily, so it suits systems where you want a strong, steady flow. A carbon block is the same carbon compressed into one dense, solid cylinder. Water has to work its way through slowly and evenly, which gives the chlorine more time in contact with the carbon — a more thorough clean — and the dense block catches fine particles as a bonus.

Neither is 'the good one'. They are teammates, and many systems use both: GAC to do the heavy lifting, a carbon block to polish the taste. One honest note: because carbon works by holding on to what it catches, every cartridge eventually fills up. Carbon cartridges should be replaced every 3 to 6 months to keep doing their job — which is exactly why our filters come with replacement reminders.

Which SUPERPURE filter fixes it in your home

If the taste bothers you at the kitchen tap, an under-counter system is the classic fix: it sits out of sight beneath the sink, and its carbon and carbon-block stages remove the chlorine taste and odour before the water reaches your glass. Renting, or can't touch the plumbing? A countertop unit does the same job with no installation at all.

If you would rather sort out every tap at once, a whole-house system treats the water where it enters your home, so drinking water, showers and appliances all benefit. And chlorine isn't only a taste issue — if showering leaves your skin feeling tight or your hair dull, a shower filter screws on in minutes and reduces chlorine before the water reaches you.

Already filtering? Fridges with water dispensers and filter jugs rely on small carbon cartridges of their own, and SUPERPURE makes compatible replacements for the big-name originals. And if you own a filter system that has started tasting of pool again, that is usually just a tired cartridge — a fresh carbon block restores the taste, and it costs less than you might think.

Not sure which filter fits your home and your water?

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