First, if the house is moving (which I doubt) don’t worry about the water line pipe, you have more important and major problems with the house moving.
My guess is that the pipe was installed and pressed down into the trench, then covered with fill to keep it down. This placed a stress on the fitting which eventually caused it to fail. The pipe may have also been bent when landscaping was installed (if any was installed) after the pipe was laid. The pvc pipe should have been placed in the trench with no stress on the pipe or the connection.
Instead of installing a pvc repair splice, why didn’t the plumber just make a proper repair by cutting out the broken area and installing a new section of pipe and fittings?
After replacing with a proper repair, cover with clean fill (sand or soil with no rocks in it). Do not put a splint on it, make sure there are no stresses on the pipe and fittings to cause it to fail again in the future. Then cover with clean fill.
[Edited by Jerry Peck on 29 November 2000]