Behind the scenes drainage

David Barker, head of Category Management at Marley Plumbing & Drainage, explores how specifiers and developers can ensure that drainage systems perform efficiently, while also being hidden from the public eye.

It is safe to say that drainage is somewhat of a taboo subject within modern-day society; after all, while everyone wants their soil and waste system to perform correctly, no one wants to be made overly aware of its presence. As a result, emphasis is increasingly placed on the ways in which specifiers can, for example, conceal pipework from sight, protect occupants from foul odours or reduce the audible sounds within a building, such as from flushing toilets or flowing waste water.

One of the main ‘behind-the-scenes’ ways of ensuring a drainage system performs efficiently, while simultaneously protecting the building’s occupants from foul odours and sewer gases, both of which could be emitted from the traps and pipes, is to correctly manage the mixture of air and water within the system.

Regardless of the system size, internal pressure will constantly fluctuate, with a sudden movement of water inside a stack – such as from the flush of a toilet – creating positive pressure in front of the flow and negative behind. In high-rise buildings, such as a hotel or apartments, there is increased potential for a large number of plumbing fixtures to be used simultaneously, especially during peak morning and evening hours. This would result in higher levels of waste water flowing through the system at any one time, in turn leading to a substantial increase in pressure instability. Negative pressure can result in ‘fall back’ of the individual trap water seals, leaving residents vulnerable to sewer gases, while positive pressure can lead to bubbles of foul air passing through the seal and entering the habitable space.

Active drainage ventilation works to control the system pressure, providing relief direct at the Point of Need (PON) by removing or attenuating an incoming pressure transient

In order to ensure that the trap seal is maintained, and the building’s occupants are protected from such offensive odours, specifiers should consider installing a form of active drainage ventilation. As the name suggests, it actively works to control the system pressure, providing relief direct at the Point of Need (PON) by removing or attenuating an incoming pressure transient. Active drainage ventilation can also be used in conjunction with air admittance valves, which, once installed, will remain closed until the system is subject to negative pressure, whereby it will then open and allow air to be drawn in, stabilising the pressure levels. Used together, they can provide a complete working system, capable of reducing pressure fluctuations and guaranteeing the trap seal retention.

Acoustics is another consideration and it is currently a big topic within the construction industry, as a number of studies have revealed the detrimental effects that nuisance noise can have on each one of us. In fact, according to the World Health Organisation, noise features along the top 10 environmental risks to our physical and mental health and wellbeing.

It is clear, therefore, that the issue of acoustics in the plumbing sector has gone beyond people simply being averse to hearing the sounds of flushing toilets or the flow of waste water from adjoining or neighbouring rooms – it is now a matter of wellbeing. Poorly specified drainage systems that create excess noise have the potential to be a real problem, particularly when they are used at all times of the day and can impact on occupants’ sleep.

There are two main types of sound for specifiers to bear in mind: airborne and structure-borne. Airborne sound refers to noise produced from vibrating air particles, such as from waste water flowing inside pipelines; whereas structure-borne sound occurs when an object impacts on another, such as pipework or fittings vibrating against the structure to which they are fixed.

Fortunately, there are a variety of solutions available that can enable specifiers to reduce both the structure-borne acoustic vibrations and also the airborne sound of flowing waste water within the pipe. For example, some manufacturers have developed acoustic drainage systems that contain specially designed pipes and accompanying support brackets, which work to reduce the levels of noise generated and transmitted from the soil system.

It is first recommended that a layered plastic pipe is specified, with each of the layers having an individual function. The inner skin is resistant to high temperatures, while the central layer provides structural strength and noise reduction capabilities, and the outer layer delivers exceptional impact resistance. This layered construction works to partially absorb sound waves and reflect them inwards, significantly reducing the transmission of noise to the system’s surroundings.

Specifiers should also consider liaising with a manufacturer that produces acoustic brackets and fixings to accompany the pipework, in order to further absorb structure-borne sound and vibrations.

Concealing components such as the cistern and pipework is becoming more common

With the rise of minimalism within bathroom design and the increasing preference for a clean, sleek and simple aesthetic, it is becoming more common for people to want to hide their soil and waste systems too, by concealing components such as the cistern and pipework. It is therefore no surprise that sanitary frames have become a popular solution, capable of supporting the wall-hung chinaware and hiding the cistern and unsightly pipework from view, as well as maximising the available space.

With this in mind, specifiers should look for manufacturers that produce sanitary frames which are fully adjustable and available in a variety of heights, making them ideal for the majority of bathroom and WC size spaces. Some also supply frames with the cistern already fitted, making for a fast and efficient installation process.

What’s more, it can be a common misconception that, because all the important system elements are concealed behind a wall or panel, access for regular maintenance or emergency repairs can be a challenge. However, some manufacturers offer sanitary frames that have been carefully designed for such situations, with easy access achieved through the flush plate.

While the main system components can successfully be hidden from view, flush plates form part of the sanitary ware that end-users will come into contact with most regularly. As such, since they can’t be concealed, specifiers should instead make an effort to ensure they are at least aesthetically pleasing. Fortunately, there are a variety of different style and design flush plates on the market to suit all bathrooms, which are also available in a range of finishes, such as glass, stainless steel and plastic.

In modern day, it is becoming increasingly common for specifiers and contractors to be tasked with concealing all visible, audible and odorous indicators of the building’s soil and waste system, with drainage viewed as somewhat of a taboo subject. However, there are a host of products available to assist in ensuring both the efficient running of the system and keeping it hidden from view. Contractors and specifiers should therefore ensure that they liaise with a reputable manufacturer that is able to provide a comprehensive array of products designed for such a purpose, as well as offer technical advice and support.