Maintaining water quality is an on going task. If you are using a municipal water supply, the city will continuously monitor the water for health factors, although many municipal residents further filter their water either for taste, odour or mineral content. People who get water out of a ground well carry the burden of monitoring their water for everything that could possibly go wrong.
Any filter or treatment system installed in your water system must be designed by a water specialists based on laboratory tests of your water. Without that initial water test, you could install an expensive system that may turn out to be useless, or worse yet, become a breeding ground for bacteria. That's why I don't like renovation centre purchase of water filter systems. You should keep a record of those tests and have the water tested once a year. Don't forget that the water sample you send to the lab has to come from the plumbing system before passing through your treatment system. If there is no significant change, you just keep on maintaining the filtration or treatment system you have according to the manufacturer's instructions. If there is a change in the lab report, you need to discuss that with your water treatment specialist to see if you need to modify your system. Remember that some treatments, like UV lamps, need to be pre-filtered to prevent the lamps from getting coated with scale and becoming ineffective. For more information check the SEARCH tab above for "Water & Health".
This is also the time of year to think about insects. There are insects that can damage us, and insects that can damage the house.
With West Nile disease moving into Canada, check carefully around the house and remove anything that will collect water and let it stagnate. Standing water is the privileged breeding ground for mosquitoes. Some landscaping will harbour misquotes more than others, so you might consider changing your garden in function of reducing the mosquito population near your house. When everyone in the neighbourhood does this, there are simply fewer mosquitoes to deal with.
Take a close look at any wood that is near or in contact with soil. Termites live in the ground and travel to eat your house, carpenter ants live in your house and travel to the garden to eat. Either way, they are both commuters and you can spot their traffic patterns. Check the SEARCH tab above for more information on "Insects".