Penny Hajduk (Letters, January 18) requests that I answer some very valid questions on the current drought which has now brought the driest period of weather to Sussex since 1914.

To do so may I first clarify that reservoirs such as the one at Park Road are underground tanks used to hold treated water prior to its daily distribution via water mains. These "service" reservoirs should not be confused with our aboveground "storage" reservoirs, for example Bewl Water, which are used to hold many months' supplies of water prior to treatment.

The old Park Road reservoir was last used 15 years ago, when it was filled and emptied on a daily basis as part of supplying water to Brighton.

Today its job is fulfilled by a larger and more modern and efficient "service" reservoir following a scheme to upgrade the water supply to the area. This reservoir is filled daily with water drawn from underground and, as many of your readers may be aware, it is these sources which give rise to concern because they are solely filled by winter rainfall percolating down through the ground.

When the old Park Road reservoir was taken out of use, all the water suitable for drinking was supplied to customers and the water encountered by developers following our sale of the site was unsuitable for human consumption. This was ten per cent of the reservoir's capacity.

However, we agree it should have been disposed of in a more responsible way and apologise that this did not happen. It is something we will ensure does not happen again.

Finally, may I assure readers we are doing all we can to tackle the drought and I would like to thank all the customers who are helping by using water wisely and not wasting it. I really appreciate their efforts.

-Les Dawson, chief executive, Southern Water