Hi all, grateful for advice from anyone with building experience. Moved into our new house in Samui last year. House is halfway down a hillside. We have a rear retaining wall about 6 feet high which we had raised by another 4 feet for security. One strange thing [ I thought] is that the blocks are vertically stacked and cemented-not staggered, with concrete support pillars every 6 feet or so. Apparently this is normal? Anyway we spent a lot of time, money and effort preparing for the rainy season-guttering, water bins, hoses etc to run the water off to the front street. Come the rainy season everything worked well initially until water started gushing UNDER the rear wall and ruining our efforts. The company who built our house [ and who have been great and very helpfull] poured cement into the areas where the water gushes out and have built a small kerb to protect our rear doors. On the other side of the wall the land is higher and the earth comes up to about 4 feet our side. The problem is that an old lady owns the land and will not let my builders or anyone else have access to sort the problem out that side i.e. drainage or rendering. It breaks my wife's heart to see all the work that she put's into the garden get washed away and she is dreading the rainy season. Sorry to waffle on- anyone got any idea's ? Would drilling holes every few feet to drain and relieve the pressure help- if so at what height. Worried now that we have blocked the waters route, we might be putting the integrity of the wall at risk with the extra pressure. Thanks for any help. Pete.

drill big holes and stick 4 inch pipe in them, then dig out the perimeter inside your wall and make a concrete drainage ditch which leads out of your land onto the highway, you can put concrete plinths or a metal grill over your drainage ditch, 20 cms wide and 40cms deep should be enough, but it depends on the length of your back wall and the amount of water trying to get in.