I know the saying is really what goes up must come down, but perhaps in the world of sewage it should be the other way round – does what go down have to come back up? Well, although we would all like the answer to be ‘No’ the reality is often different if you get a blockage!
Blockages in septic tank or sewage treatment plant systems don’t occur any more often than they do in mains sewage systems, but there are things that you can do to try to minimise these things happening.
For starters, you should never put anything to do with your car down the drain – motor oil, grease, anti-freeze, brake fluid etc can all cause blockages. Similarly, cooking oils and fat congeal easily when they meet cold water, and a horrendously revolting clag of foul smelling fat can soon build up, restricting the flow in the pipework as other substances collect on it. Trust me, you do not want to have to clean that out by hand!! Worse still, once it has got so bad, the drain may well require jetting to budge it, and there is no telling where the spray might go!
Setting the fat and disposing of it wrapped in paper in the landfill rather than washing it down the sink will obviously stop this happening. On a larger scale, however, it is always advisable for a Restaurant, Pub or Café (to name but 3) to have a Grease trap or Interceptor (no not a Jensen) installed. As the name suggests, this is a large holding tank fitted at the beginning of the drain run, through which all the waste water flows. The majority of any grease or oil in this waste settles to the bottom and can’t get back out, much like the fat which goes to the bottom of a gravy separator! The interceptor would then need to be emptied when full, just like a septic tank. This additional expense is a small price to pay to stop sewage leaching back up to the surface when it meets a blockage.
Similarly, you may think it is obvious not to put rag dolls, tennis balls, cuddly toys and whole toilet rolls down your toilet, but you would be surprised what some people (or perhaps more likely their little children) do!