Learn how to make your own solar water heater with spare parts from the kabbadiwalla. It may well cost more than the claimed amount but it will teach you how simple the technology really is. Of course, if you want to store the water, you’ll have to make, or invest in, an insulated tank.

And don’t forget to read the comments at the bottom of the post (on the Instructables site, not this one) for more low-cost ideas.

Go To: Solar Thermal Water Heater For Less Than Five Dollars

And while I was searching for more information on Sodium Acetate for the previous post on sealing concrete, I came across a way of simulating the natural patina that appears on rocks that have been exposed to air  – especially desert air.

What interested me about this information was that you can obtain different colours by varying the dilution and mixture of different metal sulphates and acetates.

Go to :: http://www.patentstorm.us/patents/5308646-description.html ^{[LINK BROKEN]}

Researchers in Jordan seem to have identified Sodium Acetate as a simple, cheap and ecologically friendly way of sealing concrete which is not my favourite material for various reasons – one of them being that the steel bars inside are prone to corrosion. This might be, at least partially, an answer to that problem.

The actual report in PDF format [~2.5 MB] via: SciGuy and: Treehugger

While discussing kitchen and bath drainage for one of the bungalows at Nasrapur, my clients wondered if ecologically safe soaps were available in India – this after I suggested we drain the water directly into a plant bed and possibly grow a nice papaya tree in it.

We spent vacations at my mum’s ancestral village when I was a kid and I remember being fascinated that, quite unlike at our city home, drain-pipes from the basin and bath just went out through the wall and pointed in the general direction of a bush. That was all there was to it. My uncle – a qualified agriculturist – who had a bungalow in Pune did pretty much the same thing but he grew small trees there. I once pointedly asked him if all the chemicals in soap wouldn’t do some long-term damage to his precious garden. He explained that phosphates and nitrates in soaps are considered bad because they promote the growth of algae which, in turn, choke water bodies by depleting the oxygen in them. But these same chemicals also promote the growth of plants so, no, there was no thing wrong with the old system.

And any of you who don’t want to chance it and would prefer to just dump it in the septic tank to be on the safe side – grey water is the last thing your septic tank needs because it considerably reduces the latter’s effectiveness by diluting the bacterial action that digests the waste. If you must send it underground, please put it directly into the soak-pit instead.