Case study — wastewater reuse in Limassol as an alternative water source

The wastewater reuse system of Limassol, the second largest urban area of Cyprus, with about 200,000 inhabitants, is in operation since 1995. The high quality effluent with an annual flow of about 3.5 million m³ is fully recycled and used for many purposes such as groundwater recharge, restricted irrigation such as public amenity areas, golf courses, etc., but excluding vegetable and similar irrigation. Wastewater reuse has the main advantage of environmental protection and upgrading whilst at the same time it offers an alternative water resource, with a marginal cost much lower than the cost of desalinated water. The marginal cost for tertiary treatment is also much less than the cost paid for dam water or desalinated water. As a result, recycled water provides the potential for the utilization of the national water resources in the most economical and efficient way, providing to the national economy great savings in real terms. In conclusion the Limassol reclaimed water reuse scheme has demonstrated in practice that domestic wastewater is a valuable resource which can and should be used in order not only to combat the water shortage in our country in an economical way, but also to upgrade and maintain the environment which is constantly under tremendous pressure and violation.

The general conclusion is that the solution of the problem of water shortage cannot be achieved in the most efficient way, through the continuous use of natural water from dams or groundwater or desalinated water. The treated effluent offers a tremendous opportunity not only to contribute to the solution of the problem but also to the upgrading and protection of our environment, nowadays facing fatal threats. The construction and operation of central sewerage systems not only in the large towns in Cyprus, but also in all the communities should be the first priority of the decision makers, merely because of its dual effect, i.e. firstly that of environmental protection and upgrading and secondly that of the potential of more efficient utilisation of the national water resources. Of course demand for water cannot be satisfied entirely by treated wastewater. In order to satisfy the water demand in Cyprus desalination is unavoidable. So, if a combination of natural fresh water, treated effluent and desalinated water is used, then a most efficient and cost effective use of the natural resources will be achieved with the average cost of water in the national economy substantially reduced.