Agreed. The EPA clearly discourage people from using the water from the hot water tap for drinking or cooking as the hot water supply may contain unhealthy sediments such as heavy metals.
A dechlorinator or water conditioner will not remove heavy metals - only an RO system or similar will be able to do that. Some conditioners may temporarily bind the metals making them less toxic for a while until they slowly precipitate back into the water.
The "Water temperature math" is fairly straight forward. If your tank is 24 C and you change say 25% with 16 C tap water (fairly typical) the resulting temperature will be 24 x 0.75 + 16 x 0.25 = 22 C - if you do it slowly no harm will be done to your livestock - I do that frequently and not as slowly as I probably should. But in your case, for just topping off, assuming that would be say 5-10% or so... again assuming your tank temp is 24 that would only impose a 0.4 - 0.8 C drop if your tap water is 16 C.
Interesting that that link still refers to lead. Is lead still in common use for plumbing in the US, or are they referring to legacy/old houses lacking updated plumbing?
In some very populous US States lead piping is still quite common in older houses - an estimated 9 million households rely on lead service lines. Its improving, but slowly.
That is interesting. I found explanations like the one below, but I assume this is not true?
Combi boiler for the win. I do exactly the same thing - no issues. I suspect even with a hot water tank the fears are outdated/overblown.
<"Flint water crisis - Wikipedia">
It is because they have <"no effective environmental legislation in USA">, meaning that it is more <"cost effective"> to supply water full of faecal coliforms and heavy metals, rather than <"wasting money"> by actually making the water safe to drink.
So a water conditioner that contained EDTA could potentially complex lead (Pb++), zinc (Zn++) and copper (Cu++) ions <"Sodium calcium edetate - Wikipedia">. Whether it actually does, or not, will depend on all <"sorts of factors"> & <"https://www.who.int/docs/default-so...chemicals/edetic-acid-background-document.pdf">.
If I was being entirely cynical about the companies that produce these types of dechlorinators (and <"Heavy Metal Axe (HMA) filters)"> I'd say they can tell you what they like (in the UK). At the moment we just don't have <"detectable levels of heavy metals"> in our tap water, so even <"secret ingredient soup"> works.
That would be true.
I don't know a definitive answer to either of those questions, lead (Pb) doesn't have any biological function (other than as a poison), but copper (Cu) and zinc (Zn) are both micro-nutrients.
Indeed, I agree (when looking at my water report at least) that heavy metals are very much not present.
Main problems is when it comes to drinking water standards in the US, is that some (predominantly low-income) communities, totally lack regular testing and enforcement.
Right. If you have elevated levels you really only can get rid of it safely with an RO system or similar.
Yes, an alternative to just pouring it in, would be to use a larger jug (bucket) and just pre-mix the cold water with some tank water to even out the temperature beforehand.
Right... Looking at shallow natural slow flowing water ways the temperature can vary quite a bit just between banks - depending on whether the water is exposed to sun vs. shade, speed of flow etc. being worried about a +/- ~2 C degree flux is unnecessary - of course in nature the fish can more to warmer or colder waters at will - but I don't think I would ever pay attention to it unless I would impose a much larger flux.
