get your drain checked,plumbers sometimes take easy way out and fit the drain from machine the wrong way,the drain pipe should be fitted into a standpipe not fitted into the u bend,this is a lazy way of doing things,all washing machines have at least 2 pints of clean water in the sump after each wash,if the drain is fitted properly you will have no prob,i bet the drain pipe from the machine is connected with a jubilee clip to a spur from your u bend
mm, May 2013