This was once a problem, but now, in the UK, the petrol we buy is clean and free from "crud", as you call it. Fuel tanks are either plastic or, if steel, coated internally. The days of rust forming inside old fuel tanks has long gone.
Any water that is in the fuel (very little in these days of sealed fuel systems), collects in the lowest part of the tank. The fuel pick up position is designed to avoid picking up water.
The Jazz (Mk 1 at any rate), has a fuel filter designed to trap any foreign bodies, and only needs changing every 72,000 miles or 6 years. However, recommendations I have read says that if the fuel pressure is within it's limits then there is no need to change the filter. As it is inside the fuel tank this is no bad thing. The filter requires a good deal of work to replace. Unless I experience fuel issues I will not be looking near my fuel filter.