Wetting agents help to prevent dry patch, reduce water related plant stress, reduce the requirement for irrigation and ensure even water distribution throughout the turf-grass root-zone. As with most problems that occur on lawns preventative is better than cure. Try not to let the lawn dry out too much during periods of drought. If it does become a problem the infected areas can be spiked to try and get the water down into the soil profile. To treat the hydrophobic area a wetting agent can be used, which is type of detergent. Wetting agents are widely used in the golf and sports turf industry to combat dry patch problems. Wetting agents reduce surface run off and help the water move through the root zone to where the water is most needed.
Any aeration before applying a wetting agent would be very beneficial and increase the effectiveness of the wetting agent.
Dry patch would only be a severe problem during very dry summers, on lawns with a light sandy soil. It should not be problem during a normal wet British summer.
It is possible to obtain a liquid wetting agent that can be dispensed via a side dispenser. The products are safe for plants and you will in fact require less water as the wetting agent makes water wetter, making it possible to penetrate dry soils easier. They are quite effective products, one litre can treat 18 golf greens for example so if an irrigation system has a 100-litre diluter, you would only require a small quantity each month to be dispensed around the garden. Localised problematic areas should be treated by hand to cure the problem as irrigation systems do not always provide 100% coverage across a lawn. This can be achieved via a hose diluter and a wetting agent tablet.