Does plumbing matter? Isn’t it just one of those things that works away perfectly in the background, and we never see or hear from it again? That’s probably what most of us think — but there are two key times when we start to take a lot more notice of it:

1. When it goes wrong. Oh yes, you’re paying attention to it now it is all over the floor!
2. When you can hear it but you don’t want to! Whether you like to listen to gurgling rainwater pipes or the sound of water falling on a tin roof, no-one likes to listen to someone else’s flushing toilets or the thud of falling water cascading down a sewer pipe and hitting the bend.

So we as designers and specifiers have a duty to get it right and to make sure that all the falls are laid to the correct minimums, so that the water can happily go down the hole and never block up, but also, so that the whole system does this quietly and we never hear a single sound. Does this really matter? Why is it more important now than it used to be? 

In the “good old days” of single family housing, acoustic treatment of plumbing and drainage was never given much attention. If there were gurgling noises coming from the plumbing, they were usually from your own house — or from your own belly! But in our new era of medium density housing, the sounds you hear could be from a neighbour's system, and ain’t nobody got time for that! Hush now!

In the Medium book (and online at www.mediumdensity.nz), we have an entire chapter devoted to services and plumbing, with a large amount of that written by a hugely respected and experienced plumber, Peter Downey. There are lots and lots of tips listed there including the obvious: make sure that the drainage point to a floor is placed at the lowest point, not the highest (as so often happens); and ensure that sewerage pipes can go straight down and not have kinks and bends anywhere near anyone else’s bedroom or living room. Straight sewer pipes make very little noise — but put a bend in the vertical dropper and everyone knows each time someone goes to the toilet. Why not take a lesson out of the commercial architect’s handbook and plan your plumbing around a common, acoustically separated plumbing and drainage riser? Even if your MDH building is only three or four storeys tall, the need for quiet plumbing is just as relevant, maybe even more so. 

In doing the research for Medium, one of the facts I uncovered was that overseas, overheard noise was a significant issue and the cause of much tension and aggression between apartment owners. That has not been evident here so far — probably because we are just at the beginning of our MDH journey, but as we densify, it is bound to rise up and be one of the primary issues in the future, if we get it wrong. So it is our task, as architects and building designers, to build so well and make sure it stays off the list completely. 

Top tips:

• Acoustically wrap any pipework that crosses another property’s space, and specify acoustic pipework as well — the thicker, heavier side walls of the acoustic pipes has a good deadening effect on transmission of sound.
• Always form a plumbing riser and if it can be shared between two apartments (mirrored in plan) then all the better.
• If you are designing one dwelling above another, install a floor waste or two, so that if the dishwasher or the washing machine breaks down and floods their floor, at least the water won’t cascade down to the neighbour’s floor below.
• Make sure not to allow any pipework to rattle or vibrate against any part of the structure, so sound cannot travel into the house, and ensure that there is an access panel opening onto a public area so the plumber does not have to do everything from within someone’s bathroom.
• Always plan out a simple solution for accessing the system for maintenance.
• Always use a Registered Plumber, and always make sure that hanging plumbing and drainage pipes are correctly restrained so that they cannot move around in a seismic event. 

Then rest easy with a good night’s sleep, knowing that you will never hear a gurgle or a splat, hopefully not a single sound at all. We only got one chance at this — we’ve got to get it right first time.