Underground Hot Water storage

[Moxi]

We seem to have wondered away from the hot water element a bit BUT the fundamental here for both hot and cold water is the volumes of storage being spoken about are simply too large.

I would suggest that how many flushes you make a day = sensible starting point for water storage from rainfall - that way you really don't have any water age quality issues and storage location relative to the point of use is much easier due to reduced size.

For hot water why not consider daily consumption as well and then consider a fundamental change to the storage parameter from hot water to warm water that way heat loss and insulation requirements reduce because the temperature gradient is low. Again this means the storage can be closer to the point of use and perhaps most usefully the opportunity to scavenge low grade heat for longer periods through the colder months becomes an option.

I would start at around 90 litres (20 gallons) but it depends on your methods for capturing rainfall ie roof size and efficiency and your location:

https://www.gov.uk/government/publicati ... or-england gives the rainfall reports for England, sorry Mart and others, ours will be on the Welsh Government pages and similarly for our Scottish brethren and anyone from Northern Ireland.

You will quickly see that filling a large tank becomes problematic because we simply do not have the volumes of rainfall required to deliver the volumes people think are available.

If like Resy you live in a water resource constrained area then it starts to get complicated/interesting as you need to consider a dual system combining grey water with rainwater, however with the high organics loading comes the issues of basic water treatment which isn't hard but does require energy and space to achieve an acceptable raw water product at the end and has some pretty objectionable sludge wastes to get shut of too so its an option only for the keen recycler and folk with some space. People that do go this route though often have a great sense of achievement as well as a greater appreciation and respect of the resource

Moxi

[Mart]

There's a chappy on the MSE forum, somewhere in England, who has mentioned his water collection / toilet flushing scheme a few times over the years. Probably over 10yrs ago now.

He had 2 or 3 IBC's in the basement, that coped for much of the year, but upgraded to 4 (or was it 5) for full year coverage*. He then uses a small pump to fill a smaller tank in the loft, for simple gravity feed for the toilets.

He isn't on mains sewerage as he has a septic tank, so reducing his metered water consumption, doesn't 'cheat' the sewerage side.

He's mentioned that he got most of the bits, including the pump free / cheap, so a very good money saver.

Obviously you don't have to use a basement, but then you have to consider storage space, and possibly the colour of the tanks or perhaps chlorine tablets (for swimming pools?), but not too complicated.

*Not that they store a years worth, but that they can cover troughs.