There's no need to suspect. A simple online visit to the local water treatment will tell you what's up, and if you have a decently run local system, it'll be updated monthly.If you suspect your source water has chlorine or chloramine, there really is no excuse for this. Just because your fish look okay... plus there is the heavy metals
Fish adapt in nature, and we have to adapt as fishkeepers. @Colin_T lives in Australia. I live in Canada. When temperatures get above 25, I dechlorinate all my tanks because I know the city will increase chlorination because of coliform bacteria loving warmth. Here, frankly, that's a few days per year. In Australia, I expect they zap the water constantly.
In the general run of things, I gas most chlorine off with agitation. I have delicate species a lot of people can't keep alive, with 2-3 year lifespans that I've maintained generation after generation for 33 years. I breed fish for fun, and easy to breed isn't fun. I try a few if I haven't bred them before, but most of the time I choose very challenging species. They thrive.
That's more than looks okay.
There's no excuse for not changing 30% of your water every 7-10 days, not stocking intelligently, not designing your tanks to fit the species in them - until there's a valid excuse or reason you haven't thought of.
Cows don't poop in my drinking water, I have no concern about temporarily binding heavy metals. If I could find a straight up, only sodium thiosulphate water treatment, I'd use it. But I don't need it.
If the World Health Organisation thinks we need to increase chlorine levels to 5mg/L after having it at 2mg/L for the last 80 years, what is in the water now that we need to kill?
Are they concerned about viruses like Covid19, drug resistant bacteria, or something else we aren't being told about?
I tend to think we're the problem, not them. We're polluting water, populations are rising and we're putting more stress on the environment. We're being told about it, but we prefer not to care or the deny it all, and so, water becomes a problem worldwide. We're fouling our nest, and fighting it with chlorine and chloramines.
By the way, chloramines don't gas off. If you have them, water treatments are obligatory.