Water, wastewater and drainage policy: consultation

5. Wastewater collection and treatment

With the changing climate more extreme weather events such as periods of very heavy and/or intense rainfall can lead to spills from our wastewater network to the environment and/or flooding to homes and businesses. Many of Scotland’s wastewater treatment works are located along the coast and are vulnerable to sea level rises. This means that we need to change our approach to managing our wastewater network. Unless we respond to the changing climate by adapting our sewage services now, the costs to households, businesses and the environment arising from floods from sewers will be much higher. We also want to maximise the opportunity to use resources from wastewater and to make it easier to adopt new and future technologies.

Additionally, to further reduce the impact on the environment from spills we need to prevent blockages in our sewer systems by making sure that we correctly dispose of our household items in bins, such as wet wipes, cotton buds, sanitary products etc. rather than flushing them down our toilets. We also want to maximise the opportunity to use resources from wastewater to support a circular economy and to make it easier to adopt new and future technologies.

5.1 Overflows^[8]

One of the most important things Scottish Water does is protect public health by taking away wastewater and rainwater from homes and businesses through a network of combined or separated sewers. During heavy or intense rainfall, more rainwater can get into the combined sewers than they can cope with, so they have been designed with an overflow mechanism which acts to safely relieve the pressure on the network and reduce the risk of flooding homes and businesses.

These overflows allow storm water (a mix of rainwater and very dilute toilet waste (usually less than 1% of the total volume)) to enter the environment. Usually, this only happens when there’s been a heavy rain downpour or prolonged wet weather, so the stormwater that is released into rivers or the sea is unlikely to cause lasting environmental damage. SEPA checks the water quality of our rivers, lochs and seas and has found that 87% of Scotland’s water environment can be classed as being in good or better condition^[9]. Where investigations confirm that overflows are not working as they should and/or causing problems for the environment, they will be prioritised for improvement by Scottish Water^[10].

Overflows play an important role within the wastewater network, and are required to allow the wastewater system to function in times of high rainfall. Removing them would require widespread rebuilding of our wastewater network to separate rainwater from the wastewater flows from our toilets, sinks, washing machines, dishwashers etc. This would be very expensive and not the best and most sustainable option in many cases. We have set out some of these challenges in the drainage of rainwater in an earlier section of this consultation. We must therefore consider more sustainable and affordable alternatives such as using new drainage infrastructures to remove rainwater from the existing combined systems and targeting problematic overflows where they have a negative impact on the quality of the water in the environment. Delivering new drainage infrastructures will take time. In the shorter term, we need to identify those overflows that are not operating correctly and that have a negative impact on the environments so we can address them.

Question

21. Should investment be prioritised to address overflows that have a negative impact in the environment?

• Yes/no

5.2 Substances / matter not to be discharged into a sewer or drain

Items incorrectly flushed down the toilet such as wet wipes, cotton buds, nappies and sanitary products, or fats and oils poured down the sink can block sewer pipes. They result in over 36,000 blockages every year that Scottish Water needs to remove. Blockages can lead to sewage spilling into the environment, or worse, into people’s homes. If the blockage causes the sewers to spill, then sewage and other items can spill into a river, loch, or the sea. These then wash up on our beaches, along the edges of our rivers and get caught in trees and plants that grow on the edges of our water environment. It is very hard to pick up this litter and it is unpleasant to look at. It costs Scottish Water more than £7 million every year to unblock the sewers and to clean up the mess, which could be used to fund other needs.

People can be fined if Scottish Water can identify who caused the blockage. Fines are imposed by a court. Prosecution is a last resort and is therefore seldom used as it is not always proportionate to deal with this problem.

Question

22. To what extent do you agree or disagree that more should be done to stop items being disposed of down toilets or drains?

• Strongly agree
• Agree
• Neither agree nor disagree
• Disagree
• Strongly disagree

23. How do you think we can change behaviours to avoid the disposal of substances or matter in the toilet/sewer (e.g. wet wipes, cotton buds, nappies and hygiene products etc.)?

• [Free text box]

24. It is already an offence for non-household properties to discharge fats, oils and greases to the sewer. Do you agree that offences should be extended to:

• include other pollutants, and specifically plastic? [Yes / No]
• extend the offence to household premises? [Yes / No]
• [Free text box]

5.3 Treatment

Wastewater is treated at a wastewater treatment works, to remove items such as wipes and plastics, solids and pollutants so that the remaining water (called effluent) is safe to put back into a river, loch or the sea. The amount of treatment depends on the numbers of people who live in the town that the treatment works serves, and the sensitivity/ classification of the river, loch or sea where the treated water will be discharged. Wastewater treatment requires energy and can involve the dosing of chemicals depending on the standards that the treated wastewater must meet, the requirements for which are set out in law.

5.3.1 Wastewater monitoring

Wastewater contains much more than human waste. It contains everything that we wash down the plughole. This includes cosmetics, soaps, disinfectants, fabrics, coatings from pans and much more. It also includes medicines that our bodies haven’t managed to absorb and germs from illnesses, like flu, that we may have. Some chemicals that we find in wastewater are problematic because they don’t breakdown in, or are harmful to, the environment such as microplastics and medicines. Wastewater treatment works are not designed to remove some of these chemicals, so we need to think of other ways to manage them. There may also be new pollutants in the future that will require different types of treatment and we need to be able to manage these too.

Monitoring at wastewater treatment works can improve our understanding of the types and extent of contaminants that are making their way into the wastewater system. Depending on what the monitoring tells us, we can take appropriate action. We can also look for pathogens that indicate diseases, such as COVID, that are in the community. This helps our health service to know whether a disease is present in a community and whether it is a big problem or not.

Question

25. We currently undertake some monitoring of pollutants, do you agree that we should extend our monitoring of wastewater to look for new pollutants, and monitor pathogens in the community?

• Strongly agree
• Agree
• Neither agree nor disagree
• Disagree
• Strongly disagree

5.3.2 Resource recovery

The solids, known as sludge, that are leftover from the treatment process contain many useful resources. Sludge is no longer seen as a waste product but as a valuable bioresource (a renewable natural resource that is derived from living organisms or organic matter). This bioresource can currently be applied to agricultural land as a circular economy alternative to chemical fertilisers or can be used to produce renewable energy. Other potential resources are lost to the environment. Recovering materials from bioresource can help to compensate for the growing use of natural resources reducing future supply risks of those that are increasingly hard to find.

There are opportunities to safely recover resources from wastewater before, during and after it is treated, helped by rapid development in technology, these include: the generation of energy; capturing heat from sewers; extracting useful chemicals, pharmaceuticals, metals and nutrients (phosphorus) etc; and reusing appropriately treated wastewaters (e.g. for irrigation or to generate hydrogen). In the future we will need to consider recovering other useful materials. Scottish Water already invests in technology to generate renewable energy and recover heat to deliver on its commitment to reach net zero emissions by 2040.

However, they can only invest in resource recovery facilities if there is an economic benefit to customers and they can continue to provide the same level of service. Any money made from these activities is reinvested in the water, wastewater and drainage services.

There are currently restrictions on using customer charges to cover upfront costs of activities that are not considered essential therefore these activities must be self-funded. This makes it difficult to explore new ideas and potential opportunities, to ultimately deliver more benefits to society.

While there currently is a limited market for recovered materials, investing in these activities would support Scotland’s circular economy ambitions and support the growth of this market.

Questions

26. Do you agree that resource recovery is something that Scottish Water should be undertaking?

• [Yes/No]

27. To what extent do you agree that Scottish Water should be able to use the money it receives from customer charges to invest in resource recovery hubs? This could include use of scarce resources and increase recycling of reusable materials that might otherwise be sent to landfill.

• Strongly agree
• Agree
• Neither agree nor disagree
• Disagree
• Strongly disagree

5.4 Private wastewater systems

Private wastewater systems are waste collection systems not connected to the public sewer, for example septic tanks. Not all properties are able to connect to the public sewer because of their location. However as new development has led to the extension of the public sewer network, it might now be feasible and desirable for some properties to connect to the public network.

Owners of properties with private systems are responsible for their maintenance and emptying. If poorly maintained, untreated sewage may enter the local environment. Whilst well-maintained systems may cause little impact on the environment, the preference is for connection to the public network to manage possible future risk, for example, poor management when properties are changing hands.

Private wastewater systems are often shared between multiple properties, making sharing maintenance difficult. There is no formal support or agreements available for householders to enable shared private wastewater systems to be maintained as necessary. However, there is provision in legislation for an owner of a shared, authorised private wastewater system that allows them to recover a proportionate share of the cost from any other owners to properly maintain the private wastewater systems.

The absence of a complete register of private wastewater systems limits consideration of where a connection to the public sewer network is feasible and cost-effective, and can also restrict the ability of authorities to check that the system is functioning well and is properly maintained. It is therefore very challenging to see where some systems may be negatively impacting the environment.

Question

28. Do you agree that all wastewater treatment systems, regardless of size or ownership, should be tested and inspected to ensure that they do not impact negatively on the environment?

• [Yes/No]

29. What support do owners and users of private wastewater systems require to best protect the environment?

• [Free text]

30. Do you think that owners of existing private wastewater systems should be required to connect to the public system where connection is possible, beneficial and not expensive?

• Strongly agree
• Agree
• Neither agree nor disagree
• Disagree
• Strongly disagree

31. Do you have any further views on public and private wastewater systems?

• [free text]