Our Drinking water comes from two basic sources, surface waters, such as rivers and reservoirs, and also groundwater. All our water has natural contaminants, particularly inorganic contaminants that come from the land and rock through which the water flows and there is to a varying extent, pollution by both micro organisms and chemicals. Usually the water from the ground is less likely to be polluted than surface water. There are a number of possible sources of man made contaminants like those from industrial premises and sewage treatment works, or run off from agricultural land and from hard surfaces, such as roads, are not so obvious, or easily controlled. Ashford Plumbers who can fit devices in pipework. Another older yet reasonably common way for contamination to happen is through a process called ‘back flow’. So how does back-flow work? Well, normally the cold water flowing into your home is high pressure. It means that the filling of your bath or the watering of your garden is really quite quick but it also makes sure that your water supply is only flowing in one direction, i.e. from the hosepipe on the lawn and into your bath tub. Lets say, there was a burst in the water main pipework down at the bottom of your street, and the supply was cut to your property for a while. If you were watering your garden at the time you may think that the hose was twisted. You lay the hose down and go and check. Whilst you are doing this, the water in your garden suddenly finds itself being sucked back into the now empty hose, and this will flow, back into the cold water mains. The water now is now free to be contaminated with lots of foreign products such as, dirt, pesticides, plant food and lots more undesirables. In order to prevent this, water regulators state that you must fit devices to stop ‘back flow’. An Ashford Plumber can fit check valves. For the hosepipe example, you should fit a ‘double check’ valve on an outside tap. This is a valve that will only allow water to flow in one direction. If it is fitted and you lose pressure, it will not let water flow back into the main supply and will not allow contamination of the water.