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The Water Crisis

Serious Water Shortages and Saving Water

All over the world the supply of water is becoming a crisis. Populations continue to increase, land irrigation demands huge amounts of water and deforestation increases surface temperature and drier micro climates. In many places where water is being pumped out of the ground water tables are falling and reduced rainfall there is insufficient water to replenish the groundwater. Here we look at the steps we can take to reduce the amount of water we use.

Water Tables and Groundwater Levels

saving water

We are facing a crisis as people continue to pump more and more water out of the ground and groundwater levels have are falling.

In the ground below our feet there is water and, rather like a lake or the sea, it has a surface. This surface is known as the water table. Its depth below the surface of the ground is dependent on many factors but, generally speaking, the water table does not reach the surface of the ground. The heat of the sun, the nature of the earth (particularly its porosity), vegetation , sea level and the shape of the ground all affect the depth of the water table beneath us.

If you walk up a hill and ground level rises the water table tends to rise with it. In limestone areas such as the Bukit where the rock is very permeable the water table tends to be considerably lower often deep within the rock. Trees have a double effect, deep roots take up moisture and can lower the water table while the shade that trees provide tend to reduce evaporation.

In rainforests with very heavy vegetation cover the water table may be shallow while in other places trees with deep roots can lower the water table. In Western Australia the excessive removal of trees has lead to rising of water tables bringing salt to the surface from the rock below causing huge areas of salt destroyed land. The answer of course would be to replant large areas of trees before the salinity takes over.

The porosity and shape of soils and rock makes things more complicated but perhaps we’ll think about that another day.

Here in Bali the water table rises during the wet season then falls through the dry season. We are now at the end of the dry season and we are starting to have some serious water problems.

Most of us, including the government water supply (PDAM), get our water from wells and bores. Obviously these must be deep enough to penetrate into the water table. To get clean, fresh water wells and bores need to penetrate well below the water table. You may find that if your well or bore only just reaches the water table you will get brackish or contaminated water. Generally speaking (but not always the case) the deeper your bore the cleaner the water you will get.

Good drainage is causing water shortages

A vital but little understood fact is that good drainage is disastrous for water tables. In cities across Australia people are starting to wake up to the fact that in populated areas three quarters of the land area is covered by road surface, footpaths, roofs and carparks which are drained into pipes which very effectively return rainfall directly to the sea. In addition swimming pools and irrigation (including watering of gardens) considerably increases the rate of water evaporation. Not surprising that under the cities the water table is falling.

Here in Bali, a place we all take for granted as being lush and green, we are starting to suffer similar problems. Too many people are taking too much water out of the ground and returning it directly to the sea.

This situation has been exacerbated in recent years by improved drainage and increased evaporation from pools and garden watering. Another lesser recognised source of water loss is the ever increasing use of swimming pool and water filtration equipment that requires regular backwashing which, once again, discharges large volumes of water into drains.

The deepening water crisis in Bali

We are now getting to crisis point. Hotel water supplies are drying up. In places near the sea where too much water is taken out of the ground sea water may penetrate into the water table inland causing salt contamination. I recently inspected a nice old house that in recent years has started to literally fall apart. Situated near the beach, rising damp is depositing salt into the brick and stone work and causing it to crumble. The house can be saved by stopping the rising damp but the reality is that this is a symptom of a much greater problem.

All over the island, particularly in lower lying areas, ground water levels are falling and rivers and wells are drying up.

How can we elleviate the water shortage

So what can we do to ease our impending water crisis?

  1. Most importantly install soak pits to return as much water as possible back into the ground. This can be not only rainwater but also grey water from showers and washing machines. Install large water tanks under houses to collect and save pure rainwater (no calcium, no sewerage or mineral contamination). The overflow from storage tanks should go into soak pits.
  2. Water the garden in the evening or early morning when it is cooler to reduce evaporation rates.
  3. Avoid excessively large swimming pools. Discharge swimming pool backwash water into soak pits.
  4. Check to see if that fancy water purification system is not using too much backwash water and make sure that the backwash water is not going into the drains. Send it to a soak pit.
  5. Install dual flush toilets.
  6. Use reduced flow shower heads.
  7. Plant trees to provide shade and reduce ground temperatures.

Many people may feel that there is little they can do but in fact this is not the case. Most of us pump water out of the ground directly under our house. This is our bit of the water table. By using less water and by returning water to it through soak pits we can all play our part in keeping water tables at healthy levels.

Copyright © Phil Wilson November 2009
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