The devastating impact of the COVID pandemic and the associated lock down has given many of us a renewed appreciation of our natural surroundings and our fragile ecosystem. The focus on climate change and the general health of our plant has to date been focused on our carbon footprint but there is now a growing understanding of the need to protect our existing ecosystems in order to slow and reverse the damage being done. Water is an important area which is often overlooked and the impact of domestic waste water on surrounding rivers and lakes is an area which needs particular focus in Ireland due to our landscapes.
In Ireland we often get the advice for householders to ensure that their domestic waste water treatment systems are properly built and maintained. There are now planning regulations and conditions, to properly test the soil percolation rates for receiving the waste water at the end of the domestic treatment system. More evidence has been collected however to show that many areas in Ireland have ground conditions that are not always suitable for receiving domestically treated waste water. There are many areas of the country where the soil conditions fail to prevent nitrogen and phosphorus getting into ground water.
The levels of nitrate pollution remaining in the water after septic tanks remains as an unsolved problem. Pharmaceuticals that were ingested by humans are also sometimes being detected in nearby well water. Except where the soil percolation rates are ideal, then phosphorus is also being detected in nearby streams. It is often the case that there is a summer smell of sewage in rural areas where there are a large density of septic tanks near small streams or with poor percolation soil.
In celebrating World Water Day 2021, perhaps today is an opportune time to consider further additional measures that should be taken by new home owners to protect nearby streams and rivers. Internationally there are increasing calls to adopt nature based solutions to address our surface water pollution problems. Perhaps then nature based systems should be used in Irish homes.
As an example, I’m suggesting the separate management of toilet solids and the separate treatment of urine by growing non-food plants. This method will remove the largest proportion of the nitrogen, phosphorus and ingested medicines that are excreted by humans. The resulting biomass would be further treated by earthworms and the long term composting of the biomass with the help of mycelium (mushrooms), in order to breakdown and reduce pharmaceuticals and antibiotics. This system would be worthwhile to install in the long run because the running costs would be so low, and the reduction of domestic waste water pollution in the environment would be so significant. The removal of urine and faeces from domestic waste water would remove about 70% to 80% of the nutrient pollution and almost all the ingested pharmaceuticals.
It’s now increasingly known that septic tanks on their own do not adequately prevent phosphorus and particularly nitrogen that so often enters groundwater or nearby streams. To illustrate the point, please see the photograph of an open tank of rainwater with added human urine, that was then exposed to the summer sun. The untreated nutrients in this tank, and from any septic tank that receives human urine, will result in algae that is most often seen on water surfaces and lakes
Please see the diagram showing a single house with an installed nature based system to avoid domestic waste water pollution. On this important day of the year, World Water Day, perhaps this, in my opinion is the most environmentally friendly method to protect our streams and rivers, and to better treat waste water with the minimum of greenhouse gas emissions.