Have you ever been somewhere where the water coming from the tap isn’t clean enough to drink? It’s very dangerous, even if you drink bottled water. When we used visit family in Bangladesh in the 1990s, we’d bring along a ton of Evian. Not only would we drink it, but the kids would take sponge baths with it, because you definitely should not shower in water you wouldn’t drink. But every time one of the kids would still get sick, because it’s hard to avoid: washing your hands in tap water, eating from dishes washed in tap water, eating fruits or vegetables rinsed in tap water, etc.

The only household uses you could use a lower grade of tap water for would be toilets and clothes washing (and then only if you run the clothes on a hot cycle).

Do you want to wash yourself or the surfaces in your house with with water you wouldn’t drink?

Why not?

Especially in the case of my hands, whatever is on my hands is likely to end up in my mouth eventually. Doubly true for infants. If you’ve ever given an infant a bath, you know that a significant amount of water ends up in their mouth one way or another.

It has been pointed out that, while replacing the existing the existing water system is infeasible, building a new, downsized system for drinking water, with the existing option being used for non-potable water, may be an option:

https://www.strongtowns.org/journal/2016/2/7/chipping-flint

Hong Kong, for example, has separate water infrastructure for salt water, which is used for flushing toilets and other non-drinking uses.

Disposable or in theory 'recycleable' plastic bottles are probably not the best option but yeah refillable 5 gallon drinking water bottles aren't a bad idea. We use them in order to get reverse osmosis filtered water from the grocery store because the water generally tastes better than tap. Even separate carbon based water filters are useful to clean tap water to a higher standard. Getting people better tasting water would probably also help people avoid drinking sugar-based soft drinks or single-user disposable water bottles.

> when 99.9% of it is not used for drinking

What is it used for? Cooking?

Showering, bathing, washing hands, flushing toilet, washing dishes, washing clothes, washing surfaces or floors (i.e. wetting and washing the rag/mop you use for wiping said surfaces), maybe watering lawns & washing cars, if I had to guess.

It's surprisingly easy and quick to run way more water than you could drink in a day just for some daily cleaning duties.

Come to think of it, I drink around 2 liters per day; that's six mugs of coffee plus maybe a couple glasses of water.

How much water do I spend when I flush the toilet once and then wash my hands? I do that quite a few times every day.

Some of those are handled more efficiently in Australia. Water tanks are required with new builds and they usually do rain collection. Those feed into toilets, lawn sprinklers, washing machine, etc. All car washes in the town also use some form of not drinkable water.

I'm not sure about the water used for cleaning though. If you want your hands to be clean before eating, why would you clean them in something your can't safely drink?

> maybe watering lawns & washing cars

Water usage is twice as high in summer as it is in winter. There's a reason why, when mandatory water restrictions go in effect, the first thing that's banned is watering lawns.

quick google found these. Not sure exactly what it is but drinking is a tiny part of what most people use.

https://www.statista.com/statistics/495373/household-water-c...

http://www.hamiltonproject.org/charts/domestic_water_use_per...