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to the table below from the BREEAM UK New Construction Technical Manual (SD5079, version 6.1). This manual contains all the relevant credit calculators. Specifying some of the new washroom innovations can therefore help increase the score by up to six points, and it doesn’t have to be expensive. Let’s look at the options. Most toilets are now available with a low fl ush or dual fl ush cistern, capable of fl ushing a toilet using less than six litres of mains water. Most dual fl ush toilets offer a 6/4 litre fl ush, some go down to a 4/2.6 litre fl ush. Most sanitaryware manufacturers list the performance of their products on the Unifi ed Water Label (UWLA) website, offering an easy reference guide for specifi ers.
Whichever toilet system you decide is right for your next project, make sure you ensure it contributes to increasing your building’s BREEAM rating
BREEAM encourages sustainable water use in the operation of a building over its lifetime, so be aware that while many claim to save on a six litre fl ush, best practice is to monitor that they deliver that performance. The BREEAM technical manual assumes one full fl ush for every three reduced fl ushes on non-domestic buildings as part of the calculation for water conservation. However, research has shown that many users don’t understand the purpose of the two buttons on a dual fl ush toilet, and some public toilets attempt to ‘educate’ users with signs suggesting that both buttons should be used to fl ush the toilet, thereby defeating the initial promise. Direct fl ushing toilets, which don’t require a cistern, are another option. Designed to suit highly frequented public toilets, this option is more expensive but, having brass valve components, can offer lower maintenance costs. While they are available as a 6/3 litre dual fl ush, saving water, theyy are also designed to reduce the risk of leaks, another sustainable advantage. Such direct fl ushing toilets however require a wider diameter water outlet, so tend to be the preserve of new builds or major renovations, not for retrofi t. Under BREEAM assessments, specifi c
toilets, such as vacuum toilets, claim to reduce water consumption by 85%, with fl ushing usage of around 1-1.5 litres. They are a solution with some compelling benefi ts, and there is no doubt about their water saving performance and ‘close to fl ush’ hygiene benefi ts. But again, the positives in BREEAM points achieved need to be balanced with a higher unit cost, a need for a dedicated water supply, extra space for equipment, and lastly, an
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electrical power supply.
A more recent innovation we have been using (eco-cistem) seems to offer many advantages. It is a component of the toilet, rather than a complete system, so it can be paired with any brand of sanitaryware. The toilet cistern uses the waste condensate water created by the building’s air conditioning units to fl ush the toilet. It can therefore only deliver its fresh water saving benefi ts if paired with an air con unit within the building. However, BREEAM points can be gained from specifying it not only due to its reduced fl ush volume, but also because it uses a grey water source, both of which factor into the credit calculation. Exact amounts of grey water used within its installation can also be easily monitored. This toilet cistern has an 18 litre twin chamber cistern that can store up to 12 litres of free condensate water above a standard six litre chamber dedicated to fl ushing the toilet. The unit prioritises using the grey water for fl ushing and only pulls in fresh water when no condensate water is available, therefore ensuring an effi cient fl ush each time with no reduction in performance if the aircon system is not in use. The installation requires that the pipework, which drains away the condensate from the aircon unit, be diverted to go into the cistern instead of straight into the waste pipe, which in most cases is a very simple diversion to plan.
The amount of condensate produced by air conditioning units will vary based on usage by country. However, even in the UK, the forecast for air conditioning unit sales is dramatically on the increase and considering a small 1.75 kW air con unit can produce over a litre of water per hour, installation will always make a substantial saving on freshwater usage. Monitors in two hotel installations in Europe have demonstrated 64% peak water savings, making them eligible for BREEAM points under WAT 01 and earning up to six points in the LEED water effi ciency category. There is a slight increase in cost to use this cistern option, so that also needs to be taken into account.
When looking at which toilet system is right for your next project, it is vital for architects to consider whether or not it contributes to increasing your building’s BREEAM rating.
David Davis is a director at MEP engineering fi rm G&H
ADF SEPTEMBER 2025
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