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The biggest headache for the pump engineer is the wet wipe

19/06/2019

The BPMA's Technical Officer Gary Wilde explains why...

The biggest headache for the pump engineer is the wet wipe, the main cause of breakdowns and callouts to pumping stations.

Reports suggest that sewer blockages in the UK caused by wet wipes being flushed down toilets are costing water companies more than £100 million (€113.5 million), amounting to approximately 200,000 blockages every year. These numbers do not include those for private households or commercial drains. About 80% of all the material retrieved from sewer blockages is wet wipes. The country’s water companies could – and should – instead be reinvesting this money into their infrastructure and overall service provision; or they could simply look at reducing customers’ bills, which would be a novel idea!

The American Arthur Julius is credited with inventing wet wipes back in 1957. Global demand for his creation is forecast to increase by 5.2% annually to over £10 billion (€11.3 billion) by 2023, with the US accounting for around 52% of this market. Supermarket shelves are full of wipe products that are branded as ‘flushable’, and for those putting these products down the toilet, the last time they will be seen is disappearing around the U-bend. However, that’s far from the end of the story. Invariably these wet wipes will end up joining a ‘fatberg’blockage in the pipework or clogging up a pump somewhere in the network. Wipe manufacturers clearly know this is a problem, and yet their marketing teams continue to promote these products as ‘flushable’. Fancy packaging, advertising slogans and recognisable logos can be confusing for shoppers, with some claims being very misleading, if not downright irresponsible. Flushable does not mean biodegradable.

Given that around 90% of wet wipes sold in the UK are not suitable for flushing, manufacturers and retailers should promote the instruction ‘do not flush’ instead of the current ‘flushable’. Wet wipes are produced as air-laid paper, where the fibres are carried and formed to the structure of the paper by air or with non-woven, spun-lace fabric; or more commonly today, as plastic textiles made of polyester or polypropylene. The tendency for wet wipes, cooking fats and other non-biodegradable solids to cling together encourages the growth of the problematic sewer obstructions known as fatbergs.

One of the largest fatbergs ever encountered in the UK was found in Sidmouth, Devon in January 2019. It was 64m in length, the equivalent of six double decker buses, and consisted of hardened fat, oil and wet wipes. It took nearly eight weeks and 36 tankers (each holding 3,000 gallons) to clear. Ordinary toilet paper degrades in a matter of hours, while wet wipes will take on average about two weeks to break down, if at all. So, for all those ‘flushing’ that take place within a short distance of a sewage treatment plant, the travel time could be anything from 2–48 hours, which is not nearly long enough for the product to degrade.

There is currently no legislation in place to differentiate between products that should be labelled as ‘flushable’ and those that should be labelled as ‘tissue’. To date, the UK Government has shown little interest in asserting new regulations, preferring to encourage wet wipe manufacturers and the water industry to develop a code of practice together. One way to deal with the issue is to fit cutter or grinder pumps at appropriate points throughout the network, but understandably these pump types usually incur high maintenance costs. Another drawback with this approach is that although the wet wipes are chopped up into smaller pieces, which helps to remove their clogging properties, it does nothing to remove the tiny plastic fibres they contain, which could potentially enter the human food chain further down the line.

Many tonnes of wet wipes, either whole or in part, that haven’t been caught up in either fatbergs or pump blockages, find their way into the inlet filters at water treatment works. These filters, which normally consist of 6mm screens fitted into the flow of incoming wastewater, are designed to catch and remove any solids prior to the main treatment process. The collected material often referred to as ‘ragging’, which includes all manner of items that shouldn’t be flushed down the toilet, such as cotton buds, sanitary products, condoms and nappies, then needs to be removed and either incinerated or taken to landfill sites.

But by far the biggest headache for the pump engineer is the wet wipe, which is the main cause of breakdowns and call-outs to pumping stations. To date, water companies in England and Wales have spent around £150 billion (€170.3 billion) improving pipes, pumping stations, sewers and treatment centres, and they continue to spend around £8 billion (€9 billion) a year to continue improvements.
There are many sewage pumps currently available on the market, all with different attributes and features, and of course technology is increasingly playing its part in helping to improve wastewater pumping. Additionally, the pump industry will continue to invest in research and development, producing new impeller designs, anti-clog systems and the likes, but one could very well argue that the only real solution is to have the problem removed at its source: better labelling on wet wipe packaging to prevent ‘flushing’, or the complete removal of this type of product from supermarket shelves.

In short, more needs to be done by wet wipe manufacturers, but it should also be the responsibility of supermarkets, the British Retail Consortium and the UK Government to address both the financial and environmental factors associated with this problem. Increased awareness amongst consumers would also help.

For more information: contact Gary  on 012 601 6692 or email him at g.wilde@bpma.org.uk


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