The flush saver you control
February 1st 2008

The Interflush water saving device is different.Whereas others deliver fixed-volume water savings, the Interflush uses only the required amount of water. Inventor David Wilks says it can save up to 47 per cent of flush water. Brendan Coyne reports

David Wilks believes the Interflush is the most effective way to reduce flush water wastage because the user controls how much water is used: A few litres is all that's needed to flush away a child's urine, whereas adult solids require more."You hold down the handle until you see the pan clear and then let go and that's it." In some cases, the full nine litres might be needed, which is where fixed-volume water saving devices, while they will save some water, can fall down, according to Wilks.

"With all fixed displacement devices,when you need nine litres for a full pan load, you haven't got it. The waste doesn't fully go round the bend, and you have to double flush, so you've lost some of your previously accrued water savings.

Secondly, if the waste does go round the bend, the danger is that there's not enough water to chase it, and it can block the drains, so you have to call Dyno-Rod. The Interflush solves all those problems: Keep your system capacity at maximum; there is always enough water to flush a full pan load when needed. Plus,when you stop the flush and the waste has just gone down the pan that's when you stop flushing there's water going down the side of the pan, in the pan ductwork and in the outlet leg of the syphon.That physical volume makes up about 1.25L of water the trailing volume and it chases the waste, eliminating blocked drain problems. And you're using the optimum volume every time."

It's a compelling argument, and one that's seen Interflush win some major customers.Wilks says it is being fitted in every branch of Barclays Bank."Barclays is doing a refit across all of its branches dubbed 'Bank of the future', and is fitting the Interflush."He says Norwich Union also plans to start fitting it nationwide around the time this issue goes to press. It will also be fitted into every Gala Bingo Hall, according to Wilks.

The device is on the Water Technology List (and in fact started the sub category 'retrofit WC flushing devices') and therefore qualifies for Enhanced Capital Allowances (ECAs).This means anyone paying business tax can reclaim both the capital and installation cost essentially a 28 per cent subsidy,making payback even faster.

The kit comes with a label that adheres to the cistern telling users to press, hold down and let go to stop.Wilks says Barclays, once the devices have been fitted, simply gather staff together and say 'the toilets now only flush when the handle is down'.

While he hasn't had any figures back from Barclays as to water savings,Wilks says Norwich Union, testing at its Norwich HQ, reduced its total building water use by 16 per cent."As a result it changed its policy all toilets now have to be syphon-based and they have to use the Interflush.The devices have paid for themselves within months." At this point, it is important to note that the Interflush device only works with syphon based toilets. See boxed text (Syphons versus valves) below for details.

So why aren't more people using it? Part of the problem, he says is that people want a quick fix solution.

The Interflush, he admits, takes around 15 minutes to fit, and it can be hard to convince potential distribution partners (ie washroom services companies) to bother learning how to do it.However, there is a step-by-step video guide on the Interflush website and Wilks says that if washroom providers are fitting urinal sleeves and water saving taps, the Interflush completes the circle, and is no more difficult to fit.

"Flushing fixed volumes is what's ingrained in people's psyche, getting the variable volume penny to drop is difficult." Alongside financial savings,Wilks believes the problem is that water is too cheap.However, he claims that will soon change "because they are going to put the cost of flood defence on the bill".

"The only thing that motivates people is money.There's a lot of green-washing going on, a lot of talk, but very little action.When people talk about avoiding the worst effects of climate change, what they are saying is 'if we are to avoid extinction'. But they don't put it that bluntly for fear of being ridiculed. I'm not frightened of being ridiculed after pushing a flushing toilet and trolley up and down the country. People can laugh, but for how long? Climate change is increasing exponentially.Writing reports doesn't fix anything.Action does."

For further information, see www.interflush.co.uk

Syphons versus valves

Wilks is passionate about what he sees as the march of the valve manufacturers "which are known to leak" against syphon-based cisterns."Syphons cannot leak, yet the vast majority of new toilets produced in this country are now push-button valvebased toilets, which results in massive annual water wastage."

Wilks' views on the subject are too strong to print, but he is not alone in recognising the problem. An article in the June 2007 Water Demand Management Bulletin, published by the Environment Agency, details how Bournemouth & West Hampshire Water's plumbing division,Aqua Care, is now considering the decision to install only syphon flushing WCs "as the number of follow-up callouts to rectify [leaking] valve flushing WCs are costing time and money".

For details, see: www.environmentagency.gov.uk/commondata/acrobat/bulletin83_final_1793034.pdf