More on my water woes.

My bore water is loaded with minerals which I do not wish to spend money on filtering and would rather use rain water in the house. I am considering constructing an underground water tank.

Does anyone have any knowledge or experience of doing this. TIA.

There was a really lengthy discussion on this subject a couple of years ago, poster Chowna had some really good inputs into it, you may want to search the forum, as I recall it may have been in the Chiang Mai forum but not sure. Anyway, loads of people build these things and basically you will need to construct what is in effect an underground swimming pool, similar construction principles apply. The biggest issue as I recall was determining capacity which unless it's really huge will only last you for parts of the year hence you will need a float that trips in and activates feeds from your domestic supply/well.

Thanks, I will try and find the posts you suggest.

As for capacity I estimate that 150,000 litres would be sufficient for a house with only two of us living in.

Unfortunantly the search function has gone bananas, but may of the build threads have tank construction in them at some stage, some on a grand scale. A common method is to put a slab floor in a pit and then rendered block walls with a preformed concrete cap.

Have you considered the Thai filtering systems using concrete rings (3 or 4 high) with different sized aggregates, all going into a separate tank of the same construction? We use this and I am very pleased with it, but we do have to clean the first layer of sand at least twice a year...

I would think there would be considerably less maintenance with something like this as opposed to all the challenges of making sure your underground tank is leach proof and leak proof. Besides, if you are only going for rain run off, remember we do have a dry season here...good luck....PP

This may help, dunno, can tell you how to mix concrete though.

http://www.thaivisa....und-water-tank/