Fish Facts – good sewage treatment is about more than just compliance

MPC Services works with domestic and commercial customers to keep their waste water systems running properly.  The obvious benefits include proper operation, reduced risk of failure, and controlling your long term costs.  For properties with off-grid sewage handling, whether septic tanks or active treatment plants, customers work with us to meet environmental compliance requirements.  Done well, on site sewage handling can improve your property and be cheaper long term than connecting to mains.


What’s that “environmental compliance” bit… 

…why does the Environment Agency care? and why should those of us who enjoy the country’s waterways care – whether walking alongside, swimming in, or boating along?

River biodiversity relies on rain water running off land and in through water tables with just the right types of nutrient.  With human development comes a range of changes, including chemical discharge from factories, fertilisers on improperly managed fields, and untreated sewage.

Excess nutrients disproportionately feed plants and algae in the river.  These grow rapidly, using up oxygen in the water, as well as blocking sunlight to organisms deeper down.  Headline impacts are algal blooms and suffocated fish.  In practice the whole river ecology is upended.  Read more at Wikipedia

What is interesting is that your sewage treatment is managing many similar processes, just in a controlled, safer environment.  Specific populations of bacteria develop in the tank, feeding on the sewage as it settles.  They use up oxygen: active (aerating) treatment plants replace this, allowing bacteria to thrive in high concentrations, converting nutrients to water and CO2; while septic tanks don’t replace the oxygen, so don’t eat so many of the nutrients before the water is discharged, and instead of CO2 they mostly give off methane – hence the name “septic”.

Have you noticed anything interesting about your treatment unit or pump station?  We would love to hear about it or see photos.  Email us at

Dam fish

While we don’t work on dams and the maintenance of fisheries, it can make for interesting out-of-hours reading.

The topic here is “how do fish get past a dam”?  Trout, salmon, and other fish have an interesting lifecycle which can involve living out at sea in saltwater, and then migrating back to the upper reaches of freshwater rivers to breed.

So what do they do when there are dams?  The UK has 486 dams.

One approach is a fish ladder: a series of watery steps and pools, routing around the main dam, up which the fish can jump.  Examples includes up the River Coquet in Northumberland, and Pitlochry Dam in Highland Perthshire.

The Ribble Rivers Trust created a more natural looking example, a rocky side-channel at Hoghton Bottoms.

At the extreme end, in America, there are working examples of so called salmon cannons: long tubes able to shoot fish across barriers, safely.

Find out more about keeping rivers clean:

– 15,000 freshwater fish:

– Eutrophication:

– EA leading efforts in the UK to keep our waterways clean:

– 486 dams: