some thoughts from Dozer
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Robin T- Water Harvest and house planning

from Robin T

image waterharvest2.jpgDue to an aberration, a cement jars holds about 2000 liters

Here are some typical figures to support the local tradition that 6 jars are enough for a family of 4 for one year. They can often supplement their needs with pond water.

  • potable water liters/day per 8 month year (dry/cold)
  • 2 adults use 5 liters/day or 1,205 per year
  • 2 children use 2 liters/day or 482 per year
  • cooking use 2 liters/day or 482 per year
  • toilet flush use 8 liters/day or 1,927 per year


  • shower use 10 liters/day or 2,409 per year
  • laundry use 50 liters/week or 1,716 per year

summary * total = 8,220 liters per year * 2000 liter jars times 6 = 12,000 liters

To this must be added, the continual rainfall during the 4 months rainy season. image waterharvest1.jpgThe average dwelling has 60m2 living space with a total roof area of 100m2 (sometimes as much as 50% bigger) Average rainfall in the Khorat plateau near Khorat is 1.165m/yr The roof can therefore yield 116m3 rainwater Nearly 10 times as is needed to keep the jars filled

(as an aside, the Thai agricultural service reckons that the evaporative losses around 2m/yr so there is a net deficit. This is the reason why farmers are encouraged to plant commercial trees, euca, mango, citrus etc so that they will keep draining the water table and prevent undesirable salts from reaching the surface and poisoning the soil). Its all a delicate balance

They have got it about right and a 6 wheel lorry can hold 6 jars which they will sell complete for 500 baht each (lids 100 baht extra). A good sound investment which will last almost indefinitely (20 years+ to my knowledge), but they must be embedded properly and drain away the overflow properly so as not to undermine the foundations. I have seen a jar explode forcibly through washed away foundations.

BTW, there is no acid rain in rural Thailand, nor other extraneous pollutants. Just keep the leaves out with a strainer and keep the lids on and weighted down with some block so they don’t blow off. See attached piccies of primary water treatment if you happen to live under trees.

There is another type of design pioneered in INDIA. Here, they make the gutters as a vee shaped strip of folded galvanised sheet placed around 2m high. The edges are bent up vertically around 50mm so as to prevent fowl from roosting (absolutely essential). There are no roof level gutters. The rain just drips down into these gullies and into the tanks. It makes for easy cleaning rather than climbing up 7m or so on a bamboo ladder. No t so pretty but maybe there is a way to disguise this. I have a design for a ground level channel and sump which might be the answer. Under all but the most severe monsoon the rain just pour straight down into these gullies, serious wind and rain don’t usually go together (in Khorat plateau anyway)

What I hope this exercise will show is the benefits of proper design work up front. Most amateurs just pile in with a bucket of money, designing on the back of an envelope as they go. The result is invariably unsatisfactory, costly and with many insoluble problems (like “house too low”.

New house builders often come from a DIY background or were a jobbing builder. Such small works never warranted full plans. Over here, IMHO, a full planning document is essential (its was always done like that in the middle east for example and was around 2 inches thick). Generally, Design services work on around 10% of the total build price (ie excluding land costs) but this only details the structure. It doesn’t include detailing of electrics, plumbing, kitchen or bathroom interiors. For a small addition you can include this as well. You might also want some interior design work done to see where you will put your furnishings etc

All in all, for about 15% of the build cost you will get a proper specification (which you can pass on as part of the house deeds, ie like keeping a log book which will easily enhance the value of your property).
The proper construction will more than pay for itself in the savings on material and time. It will also allow proper standards to be enforced on the builder and relevant inspection points to be agreed.

You might also note that expecting a builder to do your design work is a contradiction because designers work for the owner’s interests and the builder works to maximize his own profits. Think about it.

The cement jar installation is a good example, small amount of thought will bring immense benefits and save big problems.

BTW for a small extra fee, a lawyer will draw up a legal agreement based on your building spec. So why not do it properly, have fun and sleep easily at night. All enquiries contact Dozer.

editor: Yes, a lot of time can be saved by identifying important things you would like to build into your house before you start. If you just pull a design out of a book you might need to waste a lot of time later making modifications.

As far as water goes, these days it is obviously really important. Great idea is to harvest water to supplement your well or city or communal water.

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