cistern fills slow?

Look for a valve somewhere along the water inlet pipe (this could be hidden e.g. behind the pan). This valve has a small slotted screwhead. If the slot is in line with the axis of the pipes, it will be fully open; if the slot is at ninety degrees to the axis of the pipe, it will be fully closed. Half way it will restrict the flow as most probably is your case. If it is fully open and the flow is still restricted the problem will be elsewhere. To adjust use a screwdeiver to turn it to the right position.

DIYer AV
July 2008