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The Protection, Conservation, Efficiency and Re- The Protection, Conservation, Efficiency and Re-use of Water

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Our water sources are under threat due to increasing populations and present development practices of wasteful consumption and pollution. It is therefore vital that buildings do their utmost to make use of alternative water sources, and that they reduce consumption through conservation measures, greater efficiency of use and through the safe re-use of ‘waste’ water. It is estimated that with only the most basic water saving strategies it is possible to reduce water demand by up to 50% (Ref. 1). Unless we rethink our current approach to our water and sewage systems, we face the continued building of large, expensive dams and increasingly stringent water restrictions. With present increases in populations, and increasing levels of pollution there is an urgent need to safeguard future water supplies. The building industry must adopt a more sustainable approach to water use.

 

A 4-point water wise strategy would include:

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1. Protecting all water sources, i.e. eliminating all polluting activities;

2. Conserving the use of water sources, i.e. reducing the need to use water;

3. Water Efficiency, i.e. using less water through greater efficiency, as with the use of water saving devices and appliances;

4. Recycling, i.e. promoting recycling of ‘waste’ water, while being mindful of its potential to pollute local ecological systems if not properly managed.

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• Protecting all water sources:

The effluents from sewage works, detergents from households, toxic wastes from industries, run-offs from pesticides and fertilizers, acid rain, etc, are all adding to the concentrations of contaminants finding their way into water supplies. These contaminants are becoming an increasing threat to present and future human and environmental health, as they slowly accumulate within our water sources. While drinking & shower water can be filtered with water filters, this can only be seen as a short-term measure. The only long-term solution is to prevent water pollution in the first place. Furthermore, developers must realize that by altering the physical form of the environment, development can positively or negatively affect the accumulation of pollutants and the self-cleansing ability of the water cycle.

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Common Contaminants:

> Acids and acid rain

> Arsenic > Chlorine & chlorinated substances

> Bacteria & organic sources

> Fluoride

> Heavy Metals

> Hazardous household wastes

> Herbicides & pesticides

> Oil and petroleum products

> Nitrates (i.e. fertilizers)

> Phosphates (i.e. detergents)

> Radon

> Sewage and septic tank effluent

> Solvents

> Synthetic organic chemicals

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Altering the Environment: 

Inappropriate developments adversely affect water quality & pollution levels:

> The building of large dams

> The canalizing of natural watercourses

> Interfering with flood plains 7

> Destruction of wetlands

> Erosion and topsoil run-off

> Increased run-off

> Excess evaporation

> Over-use of borehole water

> Careless planning around boreholes

 

Sources of Water Pollution in the Building Industry:

Potential contaminants of water sources are best avoided. However if their use is unavoidable, then a precautionary framework for the proper and ‘safe’ handling and possible disposal of pollutant sources must be firmly in place. (See Appendix A: Construction Framework for the Protection of Water Sources).

Building Rubble –

A list of building materials potentially hazardous to water sources:

> Adhesives and glues

> Asbestos

> Fluorescent light tubes

> Paints > Paint strippers

> Transformers (old types)

> Wood preservatives

Building Materials Building Materials –

A list of materials with the potential for polluting drinking water:

> Pipes and guttering – especially asbestos & PVC plastic.

> Pipe sealants containing V.O.C’s (Volatile Organic Compounds).

> Tanks and water storage – especially asbestos & PVC plastic tanks.

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• Conserving the use of water sources:

By reducing the need to use water in the first place, it is possible to make significant water savings. Some of the strategies for achieving a greater conservation of water are outlined below:​

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Site Strategies:

• Rainwater harvesting – Collect rainwater off roofs, roads and other run-off surfaces for storage or use in:

> Rainwater tanks

> Ponds

> Swimming pools

> Underground cisterns

> Mulch pits

> Swales

> Diversion ditches

> Keyhole dams

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• Dew catching – Catch and make use of water carried in air by:

> Utilizing dew catching devices

> Retaining existing vegetation

> Planting vegetation

> Channelling and compressing air currents

> Cooling air by creating shade or providing cold surfaces

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• Reducing evaporation and landscape water demand – Reducing evaporation and landscape water demand

Help to reduce evaporation from the soil and reduce transpiration from plants by:

> Mulching the soil

> Not exposing the soil

> Providing for shade

> Planting windbreaks

> Building windbreaks

> Inter-planting/companion planting

> Planting indigenous plants

> Planting less thirsty plants

> Xeroscaping the landscape (grouping of plants according to water needs)

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• Maximizing infiltration of water into the ground – Try to hold water on the land for as long as possible, allowing for good ground water recharge by:

> Building swales

> Mulching the soil

> Building mulch pits

> Building good soils

 

Composting toilets:

Composting toilets offer a more ecological way of dealing with human waste. They recycle sewage into a harmless resource, i.e. garden compost.

• There are a number of waterless composting toilets locally available. Having relatively inexpensive installation costs, minimal maintenance and none of the usual expensive sewage treatment work overheads; these systems are highly cost effective. However some kind of soak away, grey water recycling system or regular sewage connection will still be necessary for regular shower, basin, bath, laundry, kitchen sink and other ‘waste’ waters etc. It is also possible to build your own using a twin vault system.

• Reed bed systems combine both black and grey water. Sewage is treated by creating a mini eco system, which completely cleanses all water for further re-use. Building or installing such systems would depend on local expertise.

 

− Saving Energy: Saving Energy: Saving energy saves water. For every 1 K.Whr of electricity used, we use 1,32 litres of water (Ref: 2). This is because Eskom’s process of generating power consumes large quantities of water.

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• Water efficiency:

Using less water through greater efficiency, as with the use of water saving devices and appliances.

• Efficient Irrigation – Inefficient irrigation systems and practices are to be avoided. Together with water saving site strategies, consider the use of more efficient irrigation systems, such as:

> Drip irrigation

> Dew catchers

> Grey water systems

> Soak-aways

• Swimming Pools – Much water can be lost from swimming pools due to evaporation. Consider the use of:

> Pool blankets/covers

> Rainwater collectors 9

• Water Saving Water Saving Measures Measures – Greater water efficiency is achieved through careful design and specification. Ensure proper maintenance procedures are in place and efficient plumbing with:

> Minimal lengths of “dead legs” in hot water piping through good layout design

> Balancing hot and cold water pressure

> Reducing excessively high water pressures with pressure reducing valves

> Repairing of leaks (taps, toilet cisterns, hot water systems, pipe works, etc)

• Toilets – It is possible to make great water savings with more efficient flush toilets, and is normally a priority with any water saving strategy. In an average house, toilets are normally the largest single users of water and will consume up to one third of all the water used. (Ref: 3 & 4) Consider the use of:

> Low litre flush toilets

> Manual / multi flush toilet

> Dual flush toilets

> Toilet dams, bags etc. (retrofitting device only)

> Composting toilets (combined with grey water recycling).

• Taps & Showers – It is possible to achieve a much greater efficiency with water saving fittings. However there is no point in using any of them if the hot and cold water pressures are not balanced, and if the water pressure is too high. Generally showers are far more economical than baths, with an average 5-minute shower consuming 75 litres, compared to a bath, which uses up to 180 litres (Ref: 4).

> Install flow-restrictors

> Install tap aerators.

> Install water efficient shower heads i.e. flow rates of 9-12 litres per min.

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• Recycling

Recycling grey Recycling grey water:

Promote recycling of ‘waste’ water, while being mindful of its potential to pollute local ecological systems if not properly managed i.e.

• Consider the design possibilities for recycling and redirecting ‘waste’ water that is normally channelled down storm water drains from:

> Garden taps

> Overflow pipes

> Hard surfaces

• Both grey water (used bath, shower, hand basin and laundry water), as well as black water (used kitchen sink and toilet water) are recyclable. Consider the possibilities of recycling domestic ‘waste’ water for irrigation with:

> Wet composting systems

> These cleanse and recycle both black and grey ‘waste’ waters. Such systems usually consist of a series     of ponds and reed beds, which can be incorporated within gardens or parklands as recreational             features.

> Biological grey water systems

> Such systems allow for the reuse of grey but not black water. They are designed to suit specific local         conditions. They usually consist of a series of simple settling tanks, straw and sand filters followed by         reed beds, which are planted along a swale. 10

> Mechanical grey-water systems

> Involve the use of a surge tank, and small pump, piped to an irrigation system or to a holding tank for       toilet flushing. While these systems allow for recycling of bathing, basin and washing machine water,       they exclude the use of kitchen and toilet waters. Unless a filtering system is also included, they should       only be used for sub-surface irrigation.

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