To a single microbe tap water might be harsh, to a soil population there isn't enough to cause a problem because it's in low amounts. When tap water was modernized it had to be able to support plant growth not just human digestion. There will be stuff in all tap water that can be cultured and will then go on to make you very I'll even death but never gets a chance to multiply from single numbers because of that small amount of chlorine. If water pipes get population increase and the public get Ill then an extra amount of chlorine and stuff is flushed through the pipes and were all ordered to run our taps and not drink till it's flushed out. The extra amount is the amount needed to sterelize the microbes and can harm soil life and aggrivate humans if drunk but this hasn't happened here for a long time which probably coincides with the more stable chloramine system changeover a few years back. I tell you it's easier to create a stable even solution with salts over gasses and priced cheaper so win win I think.
Our water plants can only do so much and heavily rely on the water quality of resovoirs, a dirty resovoirs with lots of dead animals might overload the processing plant so the end quality isnt so good, we have experienced this scenario too and some lands from lead mining have to be heavily managed to stop leakage because it's easy to end up in the end water supply.
We have some amazing 98 percent coverage here for good tap water, there's always going to be a few dicks that live in outlying places where supplying water is impractical and too expensive fucking up the percentage. All the info is there online about plants fish and sensitive species along with a lab quality water report. Apart from the most extreme no one changes their pH or chlorine or quality to soil grow indoors and out, there's only one concern and that's hard water. In some places after a few months you will end up with soil caked in insoluble calcium and it's accompanying friends, I'm not sure what the cut off point is in ppm, 400/500 seems high but I don't know if better standards have seen a lot of the worst places get a better.
I've not heard of desalination plants but most is just runoff rain water over land and into resovoirs, blessed with lots of mountains and rain shortages are real rare. Some times I'd taste softened water, some sewage treatments might supply back clean water as a byproduct but usually people rave about there water and think we're pretty lucky in this country.
I have no reason to fuss my tap water, I like to think it's made for the exact purposes I intend, growing food, buds, drinking, cooking and washing. If I bought soil and it killed it I would claim compensation in court, if it killed my fish or sensitive species then I have no claim as it's covered in their information given to customers and I should have read the leaflets and website.
Chlorine and pH come up a lot, neither seem relevant to soil in much detail, the ionic balances will quickly breakdown and redistribute throughout a much more complex system that we cannot give gravity to. In a resovoirs I want to hold my ph to the left of the reaction so an acid or base can push it but that's an ionic solution and the acid and base increase ppm which soil will precieve differently. Any good hydro fertilizer will buffer already by a choice selection of ingredients. All this goes to shit in soil, it's now mixed with more ingredients which would make it complex to describe the end results on a single system like pH or chlorine, your fertilizer is going to have more influence than the combined ppm of water pH and chlorine.
I really just choose soil because it's meant to be easy, no bubbling water, no throwing acid in it, no meters, sold in every shop and tap all set for me to pot and pour.
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