How Safe is our Tap Water?


Everything we wash down the plughole, as well as what seeps through the ground or falls from the sky, ends up in our water supply. This includes human waste, detergents and even hormones from women on the Pill. Other contaminants include pesticides, lead, nitrate and iron. The Drinking Water Inspectorate (DWI) is a government-regulated body that monitors and tests the UK’s water. Companies must meet stringent safety criteria. However, water still contains some minerals and chemicals that could pose a threat to our health. Studies have shown that chlorine, used to disinfect water and remove bacteria, has been linked to an increased risk of rectal and bladder cancers. The government has issued warnings about this, and research has shown a link between aluminium in water and Alzheimer’s. All tap water is heavily treated, going through several processes to make it suitable for human consumption. By 2003, the DWI announced that 99.87 per cent of all tap water tested met its standards.


Tap water
Filter it
Fruit-flavoured water
Bottled water; which is better?
Tap water varies in taste and mineral content, depending on where it comes from. According to the DWI, two thirds of British drinking water comes from surface water, including reservoirs, lakes and rivers. The rest comes from rainwater which seeps through porous rocks, then is drilled out. Some areas have hard water, which is full of magnesium and calcium compounds, while others have soft water, which is free of these. Tap water can contain traces of a range of minerals from aluminium to iron, which means the taste varies from region to region in this country. If you’re sensitive to the taste of your H2O or would like to filter it, you can invest in a jug filter (around £15). Or you water filter tap on the side of your kitchen sink. Expect an initial outlay of around £500-£700, with cartridges setting you back £100 a year.

Kenji Matsuhara

20 Responses to “How Safe is our Tap Water?”

  1. Zeb Zeb Zeb Says:

    How long do I leave the tap safe water before doing water change?
    Just about to do a partial water change to my fish tank. I was just wondering how long I should leave the tap safe water before doing a water change. ta

  2. sydney4x4 Says:

    Usually 20 mins to bring it to room temp, it will take the chill out of the water temp and wont create such a spike in the aquarium temperature when you have poured it in.
    Good Luck :-)
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  3. lulu Says:

    If you’r asking how long do you let it stand after drawing it off, I leave it 48 hours, but what is critical is that all the chlorine is removed. This can be seen as bubbles on the side of the container, stir it, if no more bubbles form, ok
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  4. Ellie Says:

    you should leave it for 24 hours in the sun light to clear it from chlorine.
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  5. Brian Says:

    Most people reccomend a 24 hour wait to help get things like chlorine out of the water. This also allows the the temperature to stabilize and time for gas exchange with the room.
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  6. Zoe Says:

    Well, you can let it sit for about a day to allow the Chlorine to evaporate.
    However, many municipalities now put Chrloramines, and traces of heavy metals, into their tap water. No amount of time will evaporate chrloramines and heavy metals which are, while not as deadly as chrlorine, toxic, and will have longterm detrimental effects on your fish. I suggest you use a water conditioner like Amquel or Stresscoat, which will neutralize all those nasty toxins.
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  7. Ghapy Says:

    If you use dechlorinator then you don’t need to age it at all – simply estimate the temperature out of the tap, add dechlorinator, and pour it all into the tank. There’s no need to over complicate the matter for a couple of reasons:

    1. Dechlorinators work instantly

    2. Temperature doesn’t need to be perfect. You are only doing a partial water change, and the smaller portion you add will heat up more quickly then the larger portion already in the tank – the end result is extremely little temperature change even if you add cool water (if you don’t believe me just try it)

    3. The only other reason you would need to let the water wait is to aerate it, but to do this you would need to run an air stone in it for the time you are resting the water. Again, because we are changing just a portion of the water, we don’t have to worry about this – the tank is already aerated and the new water will catch up quickly.
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  8. SAMANTHA F Says:

    ideally you should leave tap water for at least 24 hours, or you could shorten that time by using a water conditioner to remove the chlorine.
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  9. angelmwilson Says:

    To take chlorine out of water you can boil it or leave it for 24 hours. Or you can use chemicals made for this.

    After you have done that and have a tank set up you should only need to do about a 25% water change a week.
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  10. justin r Says:

    3 days to 3 weeks.
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    I’m an expert trust me.

  11. charger9069 Says:

    If your tank is tropical ( warm water) then just warm it up close as you can to the temperature of the water in the tank, you can do this by just making the tap water warmer. I would leave it sit for like 2-3 minutes just to make sure the chlorine is all removed, if you use chlor-X, or whatever it’s called, then it takes a matter of seconds, just make sure the temperature is as close to the tank water as humanly possible.
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  12. bella n Says:

    24 hours!!
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  13. tuvix72 Says:

    As long as temperature is close to the tank’s and you use a complete water conditioner there is no reason to age water. I perform 25-50% water changes weekly using a Python-like device, that is a hose straight from the tap to the tank. I match the temperature by mixing hot and cold tap water and I add Tetra AqauSafe to the tank both before and after having refilled it … Never had a problem.

    Letting the water sit may be required for those who don’t have hot water or are using well or RO water that is only cold. Letting it sit will also dissipate chlorine for those not using a water conditioner, but these days with heavy metals and chloramine contents it’s risky to not use a complete water conditioner.

    Tap water being under pressure initially contains higher concentrations of oxygen and CO2 than water in the tank. This dissipates quite quickly and unless you are changing more than 50% of the water it should be of no importance to you. The biggest change that occurs is a slight rise in PH as CO2 outgasses from the tap water. Not enough to require a resting period.

    Hope that helps
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  14. ispooky2 Says:

    Best do it instantly by using a proprietary dechlorinator. King British is a good one. These dechlorinators contain Sodium Thiosulphate which, as well as neutralising the chlorine, breaks the chlorine bond of the Chloramine which the water company may have added. This will release a small amount of Ammonium into the tank water, but should be dealt with by your filter.
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  15. sarah c Says:

    You can contact your water company for advice on this. A lot of people are switching to bottled water because of heavy metals, the cheap stuff from the supermarket is usually ok, but again its best to pick one with an analysis printed on the bottle or contact the company to ask them whats in their water.

    If your tap water is clean, then 24 hours in a clean bucket with an airstone will drive off all the chlorine. Adding chemicals to the water stressess fish; even if those chemicals are there to drive off chlorine.
    The chlorine is present as a gas and will disperse after 24 hours. The chemicals you add to get rid of it stay there.
    Its the metals you want to avoid.
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  16. Steven N Says:

    I would have to agree with Tuvix72. I also use a PYTHON and add straight from the tap. I change 50% water in all my tanks, 1 time a week(about 350 gallons). Tanks range from 10g to 125g. As Tuvix uses a different product, let me recommend PRIME as a water conditioner. It is excellent and goes alot further than most products(I don’t sell it LOL). Ive been doing this for years. The key as stated before is to get the water temp close to the tank temp. My house is very old(with copper pipes) and have seen no ill effects with using hot+cold water to refill the tanks.
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    5years 700g’s of fish tanks

  17. Schooling fish is my favorite Says:

    24 hours
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  18. bunnicula Says:

    I had goldfishes….they lived for 5 years and I always did a full water change each time I cleaned their tank…..I let the water stand for 1 hour and added treatment so they would not get shocked…they lived a long time!
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  19. stephen eblue eyes Says:

    24 hours so water can come up to room temp.and pour in slow,
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  20. Robert C Says:

    until it reaches room temperature
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