'Ag pipe' sounds simple - the fix is to get the water away from the back of the house so you will need to install a drain to do that. As well as a suitable sized socked ag pipe it will need aggregate and to be sloped correctly - and you need to be sure that the water ends up where it can run to storm water system - into the pipe system or the road gutters etc - and not simply move the problem to somewhere else in your yard or your neighbours!
Advice from me on this forum is general and for guidance based on information given by the member posing the question. Not to be used in place of professional advice from people appropriately qualified in the relevant field. All structural work must be approved and constructed to the BCA or other relevant standards by suitably licensed persons. The person doing the work and reading my advice accepts responsibility for ensuring the work done accords with the applicable law.