We have lived in our Victorian farmhouse for 2 years and the cellar has
always been bone dry.

In the last two weeks it has suddenly started flooding - groundwater flows
into an external sump which then backs up into the cellar. We have blocked
all the major sources of water ingress, but we are now finding water seeping
through joints in the floor which is made of brick sized blocks.

We don't know why this problem has arisen, but is there an effective way to
seal the floor? At present water is pooling on the floor.

The cellar walls are in good condition and water does not seep through them.

In case anybody asks, the sump is not deep enough to permit the installation
of a pump and float switch.

Thanks in advance

Harry