Yes, vacuum drainage can be installed in an existing building, but whether it is the right solution depends on the layout, the appliances being connected and the space available for equipment. It is particularly worth investigating when a refurbishment calls for new toilets or drainage points in places where conventional gravity pipework would be difficult to route.
That does not mean installation is possible without any building work. A retrofit still needs a designed pipe route, a vacuum plant, an electrical supply and a suitable wastewater discharge point. The advantage is that the design is less dependent on maintaining a continuous downward fall from every appliance.
In this guide, we look at where vacuum drainage can help with a refurbishment and what to check before specifying a system.
If you are looking for more information about Vacuum Drainage solutions, get in touch with us today.
Why Can Drainage Be Difficult to Change in an Existing Building?
Conventional drainage generally relies on pipework laid to a suitable fall. In an existing building, the position of the sewer connection, structural elements, shallow floor voids and occupied spaces can make a new gravity route difficult or disruptive.
This often becomes an issue when a project needs to:
- Add toilets in a basement or another area below the existing drainage route
- Move washrooms away from existing soil stacks
- Change the layout of a supermarket or commercial building
- Add drainage points without extensive work to floors
- Protect important features during a heritage refurbishment
A vacuum system may offer another route for wastewater where those constraints make gravity drainage impractical. It should be assessed against the actual building, rather than assumed to be the best option for every refurbishment.
How Does Vacuum Drainage Work in a Retrofit?
A vacuum drainage system uses a pressure difference to move wastewater through sealed pipework towards a vacuum collection plant. Vacuum toilets connect to the system through their flush valves. Other appliances, such as sinks or floor drains, may connect through vacuum interface units, depending on the application.
Because the pipework does not need a continuous gravity fall back to the collection point, designers may have more options for routing it through an existing building. Pipe size, length, changes in level and access still need to be checked as part of the system design.
Where Might Vacuum Drainage Be Useful?
Moving or adding toilets
If new toilets need to be positioned away from an existing soil stack, a vacuum system may allow a different pipe route. This can be useful when a building’s layout is changing but altering floors or structural elements would be costly.
Basement refurbishments
A basement may not have a straightforward gravity route to the existing discharge point. Vacuum drainage is one option to assess alongside other engineered solutions, including pumped drainage. The right choice depends on the site levels, appliance demand and available space.
Supermarket refits
Refrigerated display cabinets and other equipment may need to move as a store layout changes. EVDS provides vacuum drainage solutions for supermarkets that can be considered where condensate collection and future layout flexibility are priorities.
Buildings with limited space for new pipework
In some existing buildings, ceiling voids, risers and floor construction leave little room for conventional drainage routes. Vacuum pipework may provide more flexibility, subject to a survey and detailed design.
What Should Be Checked Before Installation?
A site survey is the starting point. The designer will need to understand both the proposed new layout and the drainage infrastructure already in place.
Key questions include:
- Which appliances need connecting? Record the type, number and location of toilets, sinks, floor drains or other waste points, along with expected usage.
- Where could the pipework run? Check accessible routes, structural obstacles, changes in level and any areas where work would disrupt occupants.
- Where could the vacuum plant go? It needs suitable space, an electrical supply and access for installation and servicing.
- Where will wastewater discharge? The connection to the existing drainage or treatment system must be assessed.
- What happens during a fault or power cut? The required level of service continuity should inform the plant and resilience design.
- Who will maintain the system? Serviceable equipment must remain accessible, with a maintenance plan suited to the building.
These checks are especially important in an occupied building, where the sequence of work and temporary disruption may affect the project as much as the final pipe route.
Is Vacuum Drainage Better Than Gravity Drainage for a Refurbishment?
Sometimes. If an existing building has a simple, suitable gravity route, retaining or extending it may be the most straightforward option. Vacuum drainage becomes more compelling when a gravity route requires substantial alteration, restricts the new layout or cannot achieve the required fall.
The comparison should include the whole installation: pipework and building work, plant space, electrical use, water use, maintenance and access. Both types of system need appropriate design and ongoing care.
For UK projects, drainage design must be considered against the applicable requirements and guidance, including Approved Document H: Drainage and Waste Disposal. BS EN 12109 is the British Standard for vacuum drainage systems inside buildings. The project design team should confirm which requirements apply to the particular building and location.
Can an Existing Building Stay Open During the Work?
That depends on the scope of the installation. Pipe routes and plant location can sometimes be planned to reduce disruption, but connecting appliances, installing equipment and commissioning the system will still require access to parts of the building.
If the premises must remain operational, raise this at the start of the design process. EVDS and the project team can then consider access restrictions, working hours