Keen to shake off the label as the ‘dirty man of Europe’, Britain is striving hard to reduce pollution and clean up our damaged environment. Even rivers like the Kennet and its tributaries were for too long treated as ‘free waste disposal’ carrying away industrial chemicals, metals, pesticides, and treated sewage effluent, but industry, agriculture and others have all been making changes to improve this.
Our rivers now look cleaner – but their clear waters can still hide a big problem – phosphate. This colourless chemical may not been seen, but when there is too much it can spell disaster for our rivers and their wildlife.
Phosphate is a plant nutrient, useful on land as a component of fertilisers, but in our waterways it allows nutrient-hungry algae to out-compete the natural aquatic plants like stream water crowfoot, starwort and watercress. It alters plant communities, affecting the creatures that should live there, and in severe cases causes algal blooms which use up oxygen and ‘suffocate’ aquatic insects and fish.
As well as threatening our wildlife, phosphate can prevent us from using and enjoying our streams, rivers, canals and lakes. Those who observe the Kennet around Marlborough will have seen two distinct sorts of algae: a very bright green stringy algae that grows prolifically in spring and out-competes starwort and ranunculus, and another brown coloured algae that grows on top of the green plants and smothers the whole river bed, preventing any plant growth.
Stopping this pollution isn’t easy, because phosphate isn’t just in fertiliser. In fact runoff from farmland contributes only around a quarter, and farmers have been working hard to reduce the loss of fertilisers and soils from their land.
The remainder comes from waste water generated by our homes and businesses. Despite significant improvements in waste water treatment standards, it can’t easily be removed at all water treatment works. What is more, private systems like septic tanks can’t remove it at all, so they discharge phosphate-rich effluent directly into the environment.
Perhaps unpalatably, much of the phosphate in our wastewater comes from us – it’s added to the food that we consume, such as dairy and meat products, and so ends up in our sewage. But if changing your eating habits is a big ask, there is one area where every householder can easily help to make a difference – phosphates used in domestic cleaning products account for nearly a fifth of the phosphate in our waste water. So some selective shopping can prevent this chemical being discharged into our local rivers.
Whilst the Government have taken action to reduce the amount of phosphate in laundry detergents, many other products still have a high content. Dishwasher detergents are a particular culprit with some containing over a third by weight, but low-phosphate alternatives are available – aim for those containing 5% or less.
And some manufacturers don’t use phosphate at all – so switching to brands like Ecover, Planet Clean or Faith in Nature can protect our local rivers from this damaging and rather unnecessary pollutant.
A clean house doesn’t have to mean a dirty river.
Along the Kennet, many of the larger sewage treatment works have phosphate stripping technology to reduce the amount of phosphate in effluent, but the village works don’t have this benefit. So people in villages or with septic tanks can make a real difference to the Kennet.
Want to know more? Find out about the ARK and the Kennet Catchment Partnership’s work on phosphates and on septic tanks here.
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