If you have a water based surface or a surface that can have water sprayed on to it with rain guns, you do this to lubricate the surface so that the player’s ankles can pivot safely, Without water the surface can become “sticky” and resist the ankle turning movement with the resultant risk of ankle injuries.
Two other known benefits of watering are that the water helps keep the ball flat on the surface and the second added benefit is that it reduces friction burns on knees and hands. Therefore there is a commonly held belief that when it is raining or has rained the pitch does not need watering!
• The reason why you should still water your surface is that moisture helps di-algae spores to grow and the pitch can become slippery, slimy and the spray coming off the surface from running on it stains clothing.
• A properly designed watering system will have a method of dosing the water with a heavily diluted algaecide which kills off the di-algae spores.
That is why you must still water your pitch even when it has or is raining.