VWP is a chlorine based cleaner / sanitiser. As it contains chlorine, it must be rinsed off after use, however rinsing with tap water could reintroduce microbial infections.
Failure to rinse off sufficiently could lead to high chlorine levels in the wort, which can lead to a TCP or 'sticking plaster' like aroma in the beer. If you recognise this aroma then that is probably your problem, or try searching for beer off flavours, you may fine on that matches your own experience. Treating your water with half a Campden tablet, split between the mash and sparge water as Covrich suggested should reduce this, but I believe prevention is beter than cure.
It might also be worth visiting your water suppliers website and search for 'my water quality', you should be asked to enter your postcode and it will return the test results for your supply.
A further step that many homebrewers follow is a dedicated sanitiser after the wash and rinse, chemsan and starsan are the most common, they are quite esxpensive, but a little goes a long way.
