Building Construction, Renovation, Maintenance & Advice

Water Shortage, Rainwater Catchment and Soak Pits

"Water, water everywhere and not a drop to drink"

It is said that in parts of Africa tribesmen have a clever way of trapping baboons. They take a coconut and cut a small hole in it large enough for a baboon to insert its hand. Inside the coconut they place a walnut and they fasten the coconut to a tree. A baboon comes along and puts its hand into the coconut to get the walnut but, while holding the nut, it cannot extract its hand. The baboon is doomed, through greed or stupidity (or probably both) the baboon will not let go of the walnut and so cannot escape.

There have been many versions of the story over the years, this is the one I heard over 40 years ago, but the message is still the same.

Hotels in Bali

Here in Bali there has been an epidemic of humungous proportions in recent years. No one seems to know where the disease came from and it has been unrecognised until fairly recently but it has taken a firm hold and is now disastrously affecting everyone's lives. I am, of course, talking about HIV.

Hotel Insanity Virus is taking a terrible toll on an infrastructure already creaking under the strain.
In 2001 there were around 550 hotels and 1.35 million foreign visitors to Bali, in 2015 it is estimated there are over 3,000 hotels not to mention thousands of private villas and expected foreign visitors of 4.3 million. The roads are turning into car parks, electricity supply can't cope, Bali is drowning under garbage, hotel occupancy rates are falling (64.52% in 2011, 46.02% so far for 2015) and price wars have (I am reliably informed) resulted in room rates in starred hotels falling as much as $40 per night below market rates. Already a major player in the industry has abandoned 2 new hotels which are up for sale. The hotel industry is in self destruct.

The tourism target is 30 million by 2029. The walnut is firmly in the baboons hand and, in spite of appeals for sanity from the governor and other senior tourism figures, the baboons are not letting go of their nuts.

In all this mess probably one of the most serious consequences we are facing is the most basic but essential need - water.

Bali Water Shortage

Bali is facing a major water crisis, there simply isn't enough. It is being pumped out of the ground a lot faster than it can be replenished. PDAM, the government water supply company, is not able to keep up with demand to supply piped water and those many people on the island that get their water from bores are sucking up so much that sea water is being drawn into the water tables and is progressing further and further inland.

The worst offenders for sucking water out of the ground are, as we might expect, the hotels who, in their ever increasing demand for water are drilling bores deeper and deeper. It is also reported that the more prestigious the hotel the more water they use.

The construction of a sewerage system in the southern part of Bali is considered progress from a hygiene point of view. Unfortunately it has negative consequences for the state of the water table. The water we use in our houses (much of which is pumped out of the water table) runs into the sewer and eventually to the sea. Before the sewerage system was built most of our waste water went to our septic tanks and back into the water table.

Once contaminated by sea water the water table cannot be cleaned out. Irrigating the land using saline water is a common cause of desertification as many West Australian farmers found out to their chagrin after they had cut down all the trees.

Most of don't give it a second thought, we don't even notice it but when (as I do) you see steel water tanks and pipes rusting away as a result of chlorides, sea water contamination of the ground water and houses starting to crumble away from salt laden rising damp you start to understand what the fuss is about and believe me it is closer to home and far more serious than most of us realise.

Into the future where will we find water? Desalination is perhaps an option but removing salt from water is not easy. We can use distillation in which the water is evaporated into steam then condensed back into water. We can also use Reverse Osmosis in which the water is pumped under high pressure through a membrane. Both are expensive processes both in terms of equipment and energy.

For more information you can contact the IDEP Foundation who have joined forces with Universitas Politeknik Negeri Bali and have started the "Bali Water Protection Program". I am sure they would appreciate any support or help they can get. You can contact IDEP through their website at www.idepfoundation.org

What Can We Do to Save Water?

The water crisis is, however, something we are all part of and we can all help in the solution by taking four simple inexpensive steps.

Reduce how much water we are using.

The first question is how much water are you using. It is assumed that in Bali the water consumption is 183 litres per person per day. It is estimated that in starred hotels each occupied room consumes 2,000 litres per day.

You can go to the water calculator you will find at www.mrfixitbali.com/water-usage-calculator.html to check how much your household is using. This will give you a breakdown of where you use water and so you can work out what you might do to reduce your consumption (take particular note of your swimming pool usage).

Plant trees

It is well recognised that trees improve the ability for the ground to absorb and retain moisture. Serious salination in Western Australia has been caused by removing the tree cover.

Get as much of the water around your property back into the ground.

The best defence is to allow as much non saline water (rainwater) to enter the water table in the fresh water zone and so keep the progress of saline sea water at bay.

A large proportion of land area in Australia's cities is covered by roads, car parks, pavements and buildings. Drainage systems, flood drains, subaks and rivers collect much of our fresh rainwater and carry it directly to the sea preventing it from sinking into the ground and so bypassing the water table beneath.

Install a soak pit

To get the water back into the ground you can install a catchment well or soak pit (locally known as a "resapan"and also known as a rainwater catchment absorbancy pit). A soak pit is a reverse well, a hole in the ground we put water into so it can seep away into the ground.

You can download an engineering drawing at: www.mrfixitbali.com/images/mrfixit-soak-pit.gif. NOTE that if the water is clean rainwater you do not need the filtration materials

An easily and cheaply built soak pit can be built by digging a hole in the ground and lining it using 1 metre diameter concrete rings. Depth is often about 3 metres although, of course, this depends on the ground. The soak pit needs to be deep enough to get into permeable ground so the water can soak away. The soak pit can have a concrete top on it and so the pit can be buried.

We can consider rainwater as pure water and we get it in large volumes so the soak pit can be a simple 1 metre diameter empty pipe able to hold as much water as possible. If one soak pit isn't enough you can consider installing several. Simple drainage can collect the rainwater from your property and direct it to the soak pit.

You can also return lightly contaminated water, such as grey water from washing machines, washbasins and showers to the water table by sending it to a soak pit with filtration materials installed. To make a soak pit with filtration we can fill the bottom 1.5 metres of the pit with layers of filtration materials. The design I give you here has four layers as follows:

  1. The bottom is filled with 80 cm of batu kosong (loose stones).
  2. On top of this we have a 20 cm layer of pasir (sand).
  3. On top of this a 20 cm layer of lapisan ijuk (coconut fibre as used for temple roofs).
  4. A final 30 cm layer of kerikil (coral stone).

It goes without saying that you must NEVER put unprocessed sewage into a soak pit, it MUST go into a properly designed septic tank or into the government sewer.

You might think there isn't enough space on your property to install a soak pit but you can always install one underneath the floor of your house. The pit can be buried although it is a good idea to have an access manhole in the unlikely event that it needs maintenance such as blocked filtration layers.

Most of us live on land that was formerly rice fields and rice fields are lined with clay to hold water. Much of the developed part of Bali is on the flood plain between Sanur and Seminyak, an area where ricefields overlay sediments and (close to the beaches) sand. In former rice fields it is important to dig through the layer of clay so the water will soak away into the water table.

And finally we can try to persuade the baboons to let go of their nuts.

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Copyright © Phil Wilson May 2015
This article or any part of it cannot be copied or reproduced without permission from the copyright owner.

5 September 2017 Copyright © Mr Fixit,
Jl Bypass Ngurah Rai, Gg Penyu No 1, Sanur, Bali 80228, Indonesia
Telephone: +62-361-288-789, Fax:+62-361-284-180