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Does Hot Shower Water Increase Chlorine Water Exposure?
Mar
Yes, and you can usually smell it. A hot shower lets more of the water’s chlorine escape into the air than a cool one does, which is why the smell is strongest with the hot tap on and the bathroom door shut. Icon Water, Canberra’s utility, says so on its own customer page: chlorine may be more noticeable when water is heated, such as when you run a shower or bath.
Do hot showers increase chlorine exposure?
Australian tap water carries a small amount of disinfectant on purpose. NHMRC’s Australian Drinking Water Guidelines put free chlorine in major city supplies at typically about 0.2 to 0.5 mg/L. It keeps the water safe on its way through the pipes, and some of it is still there when the water reaches your bathroom.
Free chlorine does not stay put. The same guidelines call it unstable in water and list aeration as one way it is removed, so it can leave the water and go into the air. A hot shower sprays warm water into a small room, which is about as good a setup for that as a house has.
Steam, heat and a closed bathroom door
Hot water holds less dissolved gas than cold, so chlorine comes out of it more readily. The shower head then breaks the stream into droplets, and each droplet is more surface for it to escape from.
Close the door and switch off the fan, and the room holds on to it. That is usually when people notice the swimming-pool smell. NHMRC puts chlorine’s odour threshold in water at about 0.6 mg/L and notes that some people pick it up as low as 0.2 mg/L, so two people in the same house can disagree about whether there is a smell at all.
A fan and a cracked door clear the air faster. They do nothing to the water coming out of the head.
Chlorine and chloramine in a hot shower
Not every Australian supply uses the same disinfectant. Some utilities use chloramine, which is chlorine combined with ammonia. NHMRC gives the main reason plainly: it persists for much longer, long enough to carry through very long pipelines. It also describes monochloramine as the most stable form, with the lowest tastes and odours.
So a chloraminated hot shower is a different thing. Chloramine stays in the water far longer than free chlorine, which means you are less likely to smell it in the steam and more of it stays in the water that runs over you. Which one comes out of your tap depends on where you live, and the city-by-city answer is on chloramine and vitamin C.
Taking chlorine out at the shower head
Ventilation deals with the air. To change the water itself, you treat it before it leaves the shower head, and that is what a Suhae shower filter does.
Its cartridge holds 25,000mg of vitamin C. Vitamin C reacts with chlorine and turns it into chloride, the ion already sitting in table salt, so the chlorine is dealt with in the water before it reaches the spray or the steam. KEWI certificate IW-230133 recorded 99.9% chlorine removal, and found no chlorine at six sample points from 1,000 litres through to 6,000.
A Suhae shower filter fits a standard shower fitting in about two minutes with no tools. The cartridge runs two to three months, depending on how much the household showers, and a replacement Vita Refill is AUD $29.90 in any of ten scents. How the vitamin C stage works is covered on Vitae Infusion.
A closed door and a hot tap make chlorine easier to notice. Take it out of the water at the head and there is far less of it in the steam.
