Run-off into drains, septic tanks, reed beds, streams, rivers – the environmental impact (video)

August 27, 2016

Soft washing near river & stream


A question our customers often ask: "What should I tell my customers who want to be re-assured that run-off from soft washing will not have a detrimental effect on our environment?"

Firstly, prevention is better than cure so reduce run-off at source by using skillful application techniques. Using the correct nozzles and flow rates will also significantly reduce run-off and therefore reduce risk.

Soft washing a property that is close to a stream or river

Customers can be especially concerned if their property is close to a stream or river.

The safest option if a property is close to a river would be to use Benz Bio Cleanze only, which will remain in the treated porous surface, offering long-term residual biocide protection from re-colonisation.

All residues from softwashing with Bio Cleanze are fully biodegradable without further treatment. And as this product should not be rinsed, there is no concern about rinse water entering drains or the river.

There's seldom an issue when treating with Bio Cleanze and the run-off is very slight.

Your customer would have to accept the longer timescale for results to show than if Benz Lightning Cleanze was used first to clean the worst of the contamination.



Click Here to watch the video


Lightning Cleanze does not bio-accumulate and it's surfactant is fully biodegradable.

Even so, run-off from Lightning Cleanze should not go into surface drains, which often lead into rivers.

The rinse water will only contain very small amounts of common salt and organic residue. But it should be diverted to the foul water drain where it will be treated by the local sewage works.

Most properties have sewer access near the paths, so it's usually a simple matter to divert the rinse water into the foul water system.

Quick tips:

  • Properties built prior to 1950 in the UK will probably only have foul water drains.

  • If no foul drain is available, or the local water authorities will not allow it to be used, suck up the rinse water and remove from the site in suitable containers. Then dispose of safely.

More suggestions for the safe treatment of chemical run-off and rinse water:

  1. First determine if the drains are foul or surface water drains.
  2. If foul, there is not usually a problem.
  3. Always check with the local water authority as to what they allow to go into their drains, as the regulations vary throughout the country.

Quick tip: EU regulations allow for one-off discharges of some cleaning products into drains. It is the continual or regularly repeated discharge that harms the environment. The UK regs are usually similar but it would be wise to check.

Ask for permission from the water authority to dispose of rinse water into a surface drain. Quote regulation "ERC 8E" from the “REACH Use Descriptor System” when making your application.

Block and/or divert downpipes

  • Downpipes can be temporarily blocked with rags and a tennis ball. Run-off from roofs can then be sucked from the gutters.
  • Downpipes can be disconnected and used to flow the run-off into suitable containers.


Erect dams (aka "Berms" "Dikes" and "spill containment barriers" ) to contain soft wash chemical run-off

Contain the run-off by building dams around the area being (using easily available non-absorbent barrier products such as these on Google). Then suck up the run-off with an industrial suction machine.

In hot weather the collected run-off can evaporate quickly, reducing the quantity needing to be removed from site. So it can be best to schedule final removal of the collected run-off as the final job of the day.


  • Alternatively, rinse water could be brushed to a safe (no access by humans or animals) on-site area to evaporate or be sucked up.

IMPORTANT: Septic tanks and reed beds should never have any run-off or rinse water from any chemical fed into them.

We hope this information is helpful and inspires you to succeed in soft washing.


Ben, Leo
 & Fiona,


PS: As legislation and building regulations are continually changing it would be wise to check with the relevant local authorities that our suggestions are acceptable to them, and ask if they want any additional procedures put in place. The information in this article and video pertains to EU and UK legislation and is our best understanding of the situation at the time of writing in August 2016.


    Click here to explore the full range of Benz softwash cleaning products

    Benz Softwash Bio Cleanze DDAC biocide & Benz Softwash Lightning Cleanze SH sodium hypochlorite biocide

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