The environmental consequences of neglected leaking taps

The environmental case against a leaking tap is often oversold, which is a shame, because the honest version is strong enough on its own. You do not need the scare stories. You need a couple of honest numbers and one distinction, and then the drip stops looking harmless.

The water: small drip, large year

A single steadily dripping tap wastes far more than it appears to. Sydney Water puts a dripping tap at up to around 12,000 litres a year, depending on how fast it drips, which is roughly a household's worth of drinking water poured straight down the drain.1 A tap that runs rather than drips, or a silently leaking toilet, wastes several times that again, and the toilet is worse precisely because nobody hears it. The reason the figure surprises people is that a drip is a rate, not an event: a loss of one drip a second never looks like much in any single moment, and never stops.

None of that water is dangerous. It is treated drinking water, and the loss is a waste problem rather than a health one. If you have arrived here worried that a leaking tap is contaminating what comes out of the spout, that is a separate and much-misreported question, and we answer it honestly in water quality concerns related to leaking taps. The short version: on a mains-pressure supply, the drip is escaping water, not contaminants being drawn back in.

The energy behind the water: the part most people miss

Here is the number that turns a drip from a plumbing nuisance into an environmental one. Every litre of tap water has already had energy spent on it: pumped from its source, treated to drinking standard, and pumped again through the network to your house, all of which runs on electricity that still carries a carbon cost. Waste the water and you waste that embodied energy with it. The saving from fixing a leak is therefore a water saving and a small emissions saving at once.

If the leaking tap is a hot one, the sum gets worse. Heating water is one of the largest single uses of energy in an Australian home, so a hot tap that drips is pouring away treated water and the gas or electricity used to heat it.2 A dripping hot tap is, litre for litre, the most expensive leak in the house to ignore, in both dollars and carbon.

The damp: where a leak actually does damage

There is a distinction worth drawing, because it decides whether a leak is merely wasteful or genuinely destructive. A tap that drips from the spout sends its water down the drain: wasteful, but tidy. A tap or connection that leaks where you cannot see it, under the sink, behind a vanity, at a wall connection, does something worse. That water pools, and persistent damp is how mould establishes and how timber, plaster and cabinetry slowly rot. Mould is a real indoor air-quality problem, and the structural repair of a cavity that has been quietly wet for months costs many times what the tap washer did. This is the environmental and household cost that actually compounds, and it is the reason a leak you can hear but not see is worth chasing down rather than tolerating.

Fixing it, and who does what

The good news is that a dripping tap is one of the few plumbing faults a homeowner can often make progress on. Replacing a tap washer is treated as basic maintenance in most Australian states; anything past that, and any work on the supply pipework itself, is licensed work, and because the exact line differs by state the honest instruction is to check your state or territory plumbing regulator before you go further.

It is also worth knowing why so many "fixed" taps start dripping again within months: a fresh washer pressed onto a corroded, roughened seat will not seal for long. A durable repair reseats or replaces the seat as well, or converts the tap to a ceramic disc cartridge, which is exactly the kind of detail our guide to leaking taps covers. Getting it right the first time is itself a small act of conservation: a tap that stays sealed is a leak that never comes back.

A tap that has dripped for weeks has earned five minutes at the enquiry desk: tell us what you are seeing and we will tell you honestly whether it sounds like a washer, a seat, or a job for a licensed plumber.

Sources

1. Water saving tips, Sydney Water. Source of the dripping-tap waste figure used here and the point that worn washers and seals are the usual cause; the actual annual loss depends on how fast a tap drips, and a leaking toilet wastes considerably more.
2. Hot water, Your Home (Australian Government). The evidence that so much of a home's energy goes into heating water, which is why a dripping hot tap wastes both treated water and the energy already spent warming it.