Know your drains!

By Frank Davey, a consultant with chartered, building and quantity surveyors Allman Woodcock in Norwich

Drains. So inspiring, but don’t stop reading yet, if you own a property there are things you should know. All houses have drains, some discharge to sewers, some to septic tanks and some to goodness knows where,  and we ignore them until something goes wrong.  Its better not to find out the hard way, but if you are not on mains drains there are a whole load of issues to think about, perhaps I’ll write a book but this isn’t the place to comment. As a newly qualified surveyor you get all the best jobs, and one of the most popular is to check the drains.  Back in my day you didn’t have mobile phones to drop into the chamber, but it can be a pretty unsavoury business.  There can be nasty bacteria and gases, stringent hygiene is necessary.  Its a fascinating subject though, if you’ve got the aptitude or a blocked nose. It is said that the Romans invented drains, and that in the UK the Victorians’ obsession for cleanliness was one of the best things to come out of the 19th century, introducing sanitation and public sewers.  One problem to be faced is that drains put in a hundred and twenty five or more years ago have served beyond their design life, and many of our older sewers will need to be replaced. So what can go wrong in normal domestic circumstances?  Blockages by build up of grease or things that shouldn’t be put down the loo, breakage by diverting your drive over a shallow drain or disruption by tree roots are common problems.  Please don’t plant a row of hedging right on top of the drains or the roots will find a nice source of nutrient and water and force their way in, that’s a recipe for leakage or blockage or both.  Old drains might crack through minor disturbance and if a drain leaks close to a building it can alter the subsoil conditions which could lead to subsidence. One of the first things to consider when looking at movement cracking is a drains test. Do you know where your drains go?  I had recently to consider the consequences of a drain run across a neighbour’s property in a position not allowed by an easement, that can be a big issue but otherwise you still need to know where not to plant trees or build an extension. Not all drain runs have chambers, and can be difficult to find. Well, one trick I learned a couple of decades ago is that divining rods really work, the old boy who used to do my drains tests could find cables, water pipes and drains, wet or dry.  Go on, give it a try yourself, you know you want to.  At least take an occasional look at your drains, lift the chamber covers and see where they lead.

Frank is on 01603 610243

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