Can anybody tell me any real ways to stop water bugs getting in the house?

Oh dear, NASTY NASTY WATER BUGS! As a former resident of Florida, I can tell you, they practically came with the landscape. Some of the tricks I learned over the years of living there may help you to rid yourself of the problem. We used a spray service for years, but honestly, it was costly (over time that adds up!) and I could not control where they sprayed and where they didn't. So I found some good bug spray in a large container that killed them and prevented their entry into the house. We found that the buggers were quite adept at getting in and under the sliding gl doors and inside the garage. So what I did, was go around the ENTIRE outside of the house and spray a BARRIER on every surface or entry into the house. I payed special attention to the windows and doors and sliders. Then I went inside the house and also sprayed along all the door entrys and window sills. Water bugs are rather LARGE roach looking bugs that usually live in the yards of tropical and sub tropical areas. They usually seek higher ground in rains or the rainy season and can a home with only a sliver of space as they oddly enough can squeeze under doors. Spraying a BARRIER keeps them at bay, but if they do , they will not return a second time. Do this about about once a month and you should notice a distinct decline of them into your home. If you keep up on it, you will notice they will not be coming in anymore. Hope this helps you! Good Luck!