4.—(1) For the purposes of sections 64 to 69 of the Act, “flood” means water, from any source external to a building, which enters a building—
(a)(i)at or below ground level; or
(ii)above ground level, provided that part of the body of such water is at ground level;
and
(b)does so with a volume, weight or force which is substantial and abnormal.
(2) For the purposes of paragraph (1), the following do not constitute a flood—
(a)the gradual seepage or percolation of water into a building (such as rising damp);
(b)water escaping from a water main, drain, sewer, pipe or other thing inside a building, unless such escape was solely the consequence of a flood falling within paragraph (1).