'Water conservation and effluent disposal studies should cost less than they save' says Steve Winpenny, managing director of consulting water engineers Fenland Hydrotech. He claims that very significant savings can often be achieved for a relatively low investment.
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Water. Purified and piped direct to your manufacturing plant by the local water authority, freely available at the turn of a tap, with most waste or effluent simply discharged into the public sewer. Water must be the least of your worries. Or is it?

It may come as a shock to learn that industry is paying around £1 a ton for mains water, and £2 a ton or more to dispose of effluent - and that does not include the cost of operating and maintaining pumps involved in manufacturing, cooling or cleaning processes. Even an ordinary household can use a ton of water a day, and water and effluent disposal cost one company in the snackfood industry £1 million a year. For quite a few manufacturers water supply, usage and effluent disposal are not negligible overhead expenses but substantial process costs that should be monitored and minimised. A detailed survey by professional water engineers may well reveal areas where worthwhile savings can be made, and experience shows that the cost of such a survey - and implementation of its recommendations - should be more than recovered by the savings it achieves.

The survey will check what happens to every kilo of water coming into the premises, from input to effluent - where it goes, what it is used for. First question is, what kind of water do you need, and how much? Most water is taken from mains supply, but if you are using a large amount which does not need to be potable - for cooling or washing down, for example - alternative sources such as wells, boreholes, or water recycled from other processes, may prove substantially cheaper than mains water.

For each stage of a water-intensive manufacturing process, from transport, product washing and cooling to hosing down the factory floor or yard, the quality of water should be identified and any scope for re-use defined. A great deal of water is wasted by not re-using it where appropriate, and also through leakage of pipes, joints and valves, and using more water than is necessary for certain processes. Drips and leaks from valves and washdown guns can add up to a huge amount of wastage. How long do you really need to keep water flowing through a spray bar to clean the interior of a tank?

Do you use substantial amounts of hot water or cooling water in your processes? If so, perhaps the heat can be recovered or recycled by way of a heat exchanger. However, there may be potential hygiene problems such as Legionnaire's Disease with water storage or re-use - again, professional water engineers will be able to advise on this.

Pumps are another source of wastage and high costs. Typically a pump will cost more per year to run than it cost to buy and install - a 15Kw pump will cost at least £100 per week if run for 24 hours a day, and almost every industrial pump could be more efficient. Selecting the right pump for the job is vital. People tend to install bigger pumps than necessary, and then throttle them back using the pumps' outlet valves. As a result, many pumps are running at only 30 per cent efficiency compared with the ideal of 80 per cent, and the cost of wasted energy in a pumping system may be very high. In one case this was calculated at £10,000 a year, and had been like that for ten years! Optimisation of pumping systems will include pumping the right quantity, down a pipe of the right size, with the pump operating at the peak efficiency point and optimum power factor.

Effluent disposal is another area where worthwhile savings can often be achieved. For example, dirty water is normally disposed of down metered foul drains, and surface water down ordinary storm drains. In older premises, whose drainage systems have pipes going here, there and everywhere, it is possible for surface

water to find its way into a foul drain. If this happens, the water company will charge for it at dirty water rates. There is also the 'vice versa' risk that dirty water - some of which may be highly contaminated - could get into a storm drain and hence into the nearest river… Always keep dirty water and surface water separate. And another tip; don't automatically ask your water company to dispose of badly contaminated effluent. A specialist waste disposal company may well do the job more cheaply.