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Ammonia in tap water – Easy fix?

ammonia in tap water

Ammonia in tap water often causes some confusion for us aquarists. It can make your water tests hard to read and can cause your fish additional stress if your tank isn’t cycled yet. If you have found that you have ammonia in your tap water then we have some solutions for you…….

Ammonia in tap water

The presence of ammonia in tap water can cause us some issues with our aquariums. It can give some troublesome readings from water testing and cause serious confusion if you are cycling your tank.

I have seen a few confused people recently who are performing water change after water change to reduce the ammonia level in their tank without seeing any drop at all.

This is often a telltale sign that your tap water contains ammonia in some form.

In many cases, if you detect ammonia in tap water using an aquarium test kit, it is likely that what the kit is detecting is chloramine.

Chloramine is formed by the combination of ammonia and chlorine. This compound is often added to our tap water in order to keep it clean and safe for us to drink but does no favours for our aquariums.

So what can we do if there is ammonia in tap water?


ammonia in tap water

How much ammonia can be in tap water?

Like many chemicals, there is a legal limit for how much ammonia (ammonium) can be present in our tap water. Here in the UK the limit for ammonia in tap water is 0.5ppm or 0.5mg/l.

Whilst this is a fairly low level, I am sure you can see how this could cause some issues for us aquarists.

If you were to test your water and find that your aquarium has an ammonia reading of 1ppm and conducted a 50% water change. Once you refilled it with tap water containing ammonia at 0.5ppm, then your ammonia reading in the aquarium would only decrease to 0.75ppm.

This is quite a high ammonia reading for an established aquarium to have and this quantity would certainly cause some level of discomfort for any fish that were present.

Even a 100% water change would leave you with the 0.5ppm that came in the new water.

So how can we deal with ammonia in tap water?


How can I deal with ammonia in tap water?

As we have discussed, the ammonia reading in your tap water often comes from the presence of chloramine.

Chloramine is the combination of ammonia and chlorine? So how do we deal with it?

The good news is that there are products available to help us. Those of you who have used Quantum Primer or Seachem Prime (and many other good quality dechlorinators) may have noticed that the bottle states that one of the things they remove from the water is Chloramine.

It seems that this isn’t strictly true, as an ammonia reading will still be present after using it. What it will do is dechlorinate the water, separating the chloramine molecule and removing the chlorine. This leaves behind the ammonia.

In a cycled aquarium this isn’t too much of a problem in small amounts, your filter will then deal with this ammonia very quickly and break it down, just like it does with your fish waste.

In an uncycled aquarium, this leaves ammonia behind, which for a fish-in cycle is not going to help at all and life could become very uncomfortable, if not impossible for your fish.

Just another reason why fishless cycling is the better route.

Ammonia in tap water whilst doing a fishless cycle is perfect! It could save you buying a bottle of ammonia or throwing fish food in to create it. Free ammonia is a win for fishless cycling. (You will still need to use a dechlorinator though!)


ammonia in tap water

Other options for ammonia in tap water

If you do find yourself in the predicament of having ammonia in your tap water then there are some other options available to help too.

RO water is widely available and is usually sold in 20l containers at most aquatics shops. RO water is stripped of all impurities, it is very pure.

This means it is ideal as an alternative if your tap water contains ammonia, but please ensure you re-mineralise it if you use it, particularly if using 100% RO!

RO water is so pure that its KH value is zero. This means that it cannot maintain a stable pH. This is why it needs to be re-mineralised.

You could even invest in your own RO filter.

Another alternative is HMA filtration. HMA filters can be purchased fairly cheaply and some will remove chlorine and chloramine from water (they usually require a carbon stage of filtration to achieve this).


ammonia in tap water

Bottled solutions?

There are many bottled (and unbottled) products that say that they will ‘lock up ammonia’, or similar wording, I would not rely on these to solve the issue of ammonia in tap water, or in the aquarium at all.

Even products like Seachem prime, which is relied upon by aquarists the world over, has not been proven to detoxify ammonia.

99% of aquarists on social media will tell you that Seachem Prime will detoxify ammonia and nitrite for 24 or 48 hours.

The Seachem website also states that prime will bond with ammonia and nitrite for up to 48 hours but sadly, I have found no published scientific testing that shows that it is actually capable of this.

So it cannot be relied upon.


Ammonia in tap water

If you do find that you have ammonia in your tap water then it shouldn’t cause an issue if your aquarium is mature and cycled.

Certainly not within the UK legal limits for what tap water can contain.

If you are currently fishless cycling your aquarium then even better, you now have a free source of ammonia that will save you a few pennies as you won’t need to add as much of it in order to grow your filter bacteria.

If you are fish-in cycling and have ammonia in your tap water then unfortunately it may cost you a few quid. You will need to start using RO water and re-mineralising it before use, or you may need to invest in an RO or HMA filter that is capable of removing chloramine and/or chlorine and ammonia.



How much ammonia is allowed in tap water?

Here in the UK, the limit for ammonia in tap water is 0.5ppm or 0.5mg/l.

What can I do about ammonia in my tap water?

If you find that there is ammonia in your tap water then there are a few options for dealing with it. In a cycled aquarium it is unlikely to be of consequence but in a newer aquarium, you may need to consider RO water or another type of filtration.



Anglian Water

RO man

About the author

James @Seriously Fishy

I am a fish keeping enthusiast with over 20 years experience. I currently keep American Cichlids (CA) which are my favourite fish to keep so far. I started Seriously Fishy as I noticed a large volume of people on various web pages looking for help with Aquarium basics. I created the first Seriously Fishy book to solve the issue in 28 pages, that led to the Seriously Fishy UK fish forum and blog.

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  • Hey! This article was helpful.. however.. I’m in a predicament and need advice. There is between 0.25-1ppm of ammonia in my tap according to my freshwater test kit. I own axolotls and they cannot tolerate ammonia well at all. I have been cycling my tank for 3 months and it keeps seeming to be cycled… and then I do a water change and it no longer processes. It’s like the ammonia in my tap is different than the ammonia I bought from Dr.Timms.

    Another problem… I started buying RO water from primo. And I even purchased my own RO buddy. With both my own filter and the store filter it does not take the ammonia out of my city’s water 🙁 I have doing a fishless cycle but in the meantime I’m rubbing my axolotls and doing daily water changes. But I’m so stressed because until I buy bottled water I cannot avoid the cities ammonia. Any ideas?

    • Hi Coral. Sounds like a nightmare! As far as the ammonia goes, it comes in many different forms. The ammonia in tap water is usually in the form of chloramine (Ammonia + Chlorine). Your dechlorinator should remove the chlorine from it which would then be ‘removed’ by your cycled filter.

      If this isn’t happening then it may be that your filter isn’t quite cycled to deal with the level present in your tap water. How long has the tank been running?

      If ammonia is still showing after using only RO water then the issue may well be that the filter just hasn’t cycled yet.

      The other option of course is that your test kit is not giving a correct reading, it could be out of date etc.