Hard water - not filtered by water board?

Filtering doesn't remove the lime content of water

They may want the pipes (or the ones to your house) to scale up if the area still has a lot of lead. It stops the lead leaching into the water.

I would thought this is for two reasons: cost and the fact that a small amount of the salts which cause limescale is actually thought to be beneficial to the human body.

And it's not filtration, which the removal of solid particles from a liquid by a fine mesh (metal, paper, ceramic). In the case of hard water, the salts are dissolved in the water and gradually deposit themselves onto the pipes in your house. You'd need a chemical reaction in the treatment plant to convert the salts to something insoluble that would precipitate out - *that* precipitate could be separated by filtration.

Then WTF is a limescale filter that people fit into their homes? Why not do this filtering earlier?

So what do "filters" for preventing limescale buildup do in your house? Make sure it stays dissolved?

It is also expensive and only really matters for some things like making tea - too much calcium and you get a layer of brown scum on top. The right hardness matters for coffee too but only affects the taste.

Some of them do nothing at all. The magnetic snake oil variety.

The real water softening filters swap calcium ions for sodium and have to be replaced or recharged from time to time. It is a waste softening water unless it is for drinking or some other critical usage that requires soft water. Hard water doesn't corrode pipes and may even seal minor pinhole leaks - which is a benefit for the water company.

They are not filters but ion exchange resin beds that exchange the calcium in the water for sodium. You must regenerate the resin by adding salt to flush out calcium to sewer.

But if you get continuous deposition in the pipes, after some amount of time no water flows.

More than 15 million U.S. households have their own well. Some of them don't see fit to treat their water for calcium.

Cindy Hamilton

I was thinking more of clogging up combi boilers.

You'd think anyone posting here would know that, wouldn't you.

Depends where you live. I don't know about the US, but in the UK only the south half has hard water.

Their pipes don't scale up.

Not me, I live in Scotland where we have soft water. I was just asking out of interest.

Why not?

Except in insanely hard water regions it requires evaporation and exactly the right pH for calcium carbonate to plate out at any speed. These conditions are not normally met in a pipe unless there is a leak.

Heating it in a kettle or boiler is the most common source od problems with hard water since that does make it come out of solution quickly.

I recall some drain pipes in a former dye chemical plant that were hugely entertaining when removed after the plant was closed. I believe some clocks and other ornaments were made from polished sections of it. Heaven knows what noxious ancient aniline dyes were in there.

Everyone should know but when you hear that maybe 20% of a population is functionally illiterate, i.e. cannot read beyond road signs or newspaper headline, it makes one think that technical illiteracy is even higher.

Might also have mentioned reverse osmosis which even less probably understand and is a filtration of sorts and more expensive process.

OK.

Ha yes, I decoked the kettles and the urn at our village hall a few weeks ago. That took ten of the lactic acid sachets.

This *is* a UK group.