Preventing water pollution
Water pollution can come from a number of different sources. Many solids, liquids and gaseous substances can cause pollution if they enter the water environment. Common pollutants include chemicals, oil and waste products. Even substances such as milk, which pose no risk to human health, can cause serious harm to the water environment.
You must have authorisation if you discharge anything other than clean, uncontaminated water to surface waters or groundwater. Surface waters include rivers, reservoirs and canals, and make up a small percentage of fresh water reserves. Groundwater is all water below the water table. Groundwater makes up the largest available reserve of fresh water.
This guide outlines the main causes of water pollution, and when businesses need to apply for surface water or groundwater authorisations. It also describes how to prevent water pollution incidents and gives tips on suitable drainage systems.
Causes of water pollution
Water pollution has damaging effects on the environment, humans, plants and animals. Pollution can occur if your business discharges substances into surface waters or groundwater without prior treatment or by accident, eg after a spill.
The most common causes of water pollution include:
- spills or leaks from oil and chemical containers
- trade effluent going into surface water drains instead of foul water drains, or straight into watercourses
- removing too much water from surface waters and groundwater
- run-off containing fertilisers and pesticides from farming into surface waters
- run-off containing salt during winter months
- silt and soil from construction sites and bank erosion on farms
- wash waters and waste products
- fuel spills
- releases of hot water
- spills of food products, eg dairy products and fruit juice
If you pollute the water environment, you may be committing an offence.
Surface waters and groundwater are protected by a number of licensing regimes that prevent and control water pollution from businesses.
Point source and diffuse water pollution
Point source water pollution occurs where pollution comes from a specific, identifiable source, such as a sewage pipe or factory wastewater pipe.
Diffuse water pollution is caused by various sources, which are often hard to identify. Individual sources may be relatively small, but the combined effect of numerous sources can be damaging. Diffuse pollution has a greater impact on the water environment than any other source of pollution.
In rural areas, sources of diffuse water pollution include:
- run-off from agricultural land containing substances including pest control products, animal medicines, slurry, sewage sludge and manure
- run-off and leaching from contaminated land
- silt and dust from mining, quarrying, construction and demolition
- groundwater drainage discharging from disused mines
- incorrect waste pipe connections
In urban areas, sources of diffuse water pollution include:
- pollutants from car parks and transport, such as oil and brake fluid, rubber and metal from tyres and brakes, exhaust emissions, and detergents and grease from vehicle cleaning
- heavy metals and pollution washed from roofs
- animal faeces, for example from dogs and birds
You can prevent diffuse water pollution by:
- using sustainable drainage systems to control diffuse pollution from lightly contaminated run-off
- fencing off areas and establishing cover to prevent soil erosion
- using silt traps, buffer strips and sand bags to prevent run-off containing sediment from polluting surface waters and groundwater
- storing and handling hazardous materials carefully to prevent diffuse pollution from leaks and spills
Regulation that protects surface water and groundwater
Surface waters and groundwater are protected by a number of different regulatory controls. These protect water from pollution, prevent water sources from being depleted and control interferences with the natural flow of water.
You must apply for a discharge consent or groundwater authorisation if you want to discharge anything other than clean, uncontaminated water to surface waters or groundwater. Surface waters include rivers, loughs, reservoirs and canals. Groundwater includes all water below the water table.
NIEA can issue notices to businesses to control water pollution.
If your business activities pose an imminent threat to the environment, you must notify the relevant enforcing authority if the threat continues and take steps to prevent environmental damage. Where environmental damage has already occurred you must take action to remedy the damage.
You may need a trade effluent consent or agreement from Northern Ireland Water before you discharge trade effluent (liquid waste) into a public foul sewer.
You must have an abstraction licence from NIEA if you take certain quantities of water from surface waters or groundwater, or an impoundment licence if you impound (store or dam) water on an inland waterway.
You must make sure you store and use hazardous substances safely to avoid causing harm to human health or the environment.
If you have a farm in a nitrate vulnerable zone (NVZ) - an area designated as being at risk from agricultural nitrate pollution - you must comply with specific rules.
If you pollute water or carry out certain activities without the necessary authorisation you may be fined, or even sent to prison.
Types of water pollution notice
If your business activities cause a risk of water pollution, or lead to a water pollution incident, you can be given a water pollution notice.
The Northern Ireland Environment Agency (NIEA) can issue you with different types of notices to prevent and control water pollution including:
- works notices
- enforcement notices
- prohibition notices
- prevention notices
- remediation notices
Water pollution works notice
NIEA can issue you with a water pollution works notice to prevent or clean up surface water or groundwater pollution, including water in the ground both above and below the water table. For example, if a polluting substance is likely to enter surface waters or groundwater you may be required to take precautionary action, such as using a secondary containment system. If you have caused pollution you may have to remove the polluting matter and repair any damage to the environment.
Water pollution enforcement notice
Enforcement notices are similar to water pollution works notices but are used if you have a permit or consent. You may be issued with a water pollution enforcement notice if you have breached, or are likely to breach, the conditions of your permit or consent. The notice sets out what you must do to comply, and the deadlines by which you must take corrective action.
Water pollution prohibition notice
NIEA can issue you with a prohibition notice to stop you from carrying out an activity that might directly or indirectly pollute any waterway or groundwater.
Water pollution prevention notice
If your activities could cause environmental damage to water, land or biodiversity, you must take all practical steps to prevent any damage and, if the threat remains, report it to NIEA. NIEA can issue you with a water pollution prevention notice that requires you to take action to prevent environmental damage.
Water pollution remediation notice
If your activities do cause environmental damage, you must take all practical steps to prevent further damage, report the damage to NIEA and remediate the damage. NIEA can issue you with a remediation notice that requires you to repair the environmental damage within a certain period.
NIEA can serve notices on you to prevent or remedy water pollution if:
- they think it is likely that you are causing, or will cause, a polluting substance to enter surface waters or groundwater
- you break the conditions of a discharge consent
If you cause water pollution, NIEA can also remedy the damage itself and charge you for the work.
Three top tips to prevent water pollution
Almost any type of solid, liquid or gaseous substance can cause water pollution. However, there are practical ways you can minimise the risk of causing water pollution incidents.
If you have a pollution prevention and control permit or waste management licence some of these measures may be included as conditions of your permit or licence, which you must comply with.
1. Store and handle materials carefully
It is important that you store and handle materials in a responsible way. For example, you should:
- store hazardous substances according to the manufacturer's instructions
- label containers clearly and accurately
- keep the smallest amount of materials necessary
- store incompatible substances separately eg chemicals that may react with each other
- make sure you are aware of restrictions on the way you can use chemicals
- train your staff to store and handle substances properly
- take extra care when you handle and transport materials
If you store oil, such as petrol or diesel, in containers there are certain legal requirements that you may need to comply with.
2. Prevent pollution from uncontrolled releases or leaks
Put in place measures to prevent uncontrolled releases or leaks from causing pollution. For example, you should:
- Mark loading and unloading areas and isolate them from the surface water drainage system. If this is not possible, protect surface water drains using sandbags, mats or other devices.
- Store all above-ground storage tanks, drums and containers on an impermeable base within a drip tray, bund or any other suitable secondary containment system to contain any spills - download pollution prevention guidelines on above ground oil storage tanks (PDF, 507K).
- Install drip trays, or other forms of containment, beneath any equipment that is likely to leak or result in spills of pollutants. Empty drip trays regularly so that they do not overflow. You may need to dispose of the contents of the trays as hazardous waste.
- Have procedures to prevent pollution from your drainage system, eg keep an updated drainage plan and colour code your drains.
3. Be prepared for pollution incidents
Be prepared for an accident at your site. For example, you should:
- prepare a pollution incident response plan and train staff on how to implement it
- keep absorbent materials, such as sand and other containment equipment, suitable for containing the type and quantity of substances you store and use on your site and make sure your staff know where they are
- make sure your site and storage areas are secure at all times, particularly outside of normal business hours, so that containers cannot be tampered with
You may be liable for pollution that occurs as a result of damage caused by intruders.
Drainage system requirements to avoid water pollution
You should have a good working knowledge of your drainage systems. There are two types:
- Separate drainage systems have two drains, one for foul water and another for surface water. The foul water drain carries polluted water, such as sewage and trade effluent, to a sewage treatment works. The surface water drain should only carry uncontaminated rainwater as it goes directly into a watercourse.
- Combined drainage systems have a single drain that carries both foul and surface water to a sewage treatment works.
If you want to discharge anything other than clean, uncontaminated water into a surface water drain, or directly into surface water or groundwater, you must have a discharge consent from the Northern Ireland Environment Agency (NIEA).
If your business discharges trade effluent to a public sewer, you must have a valid trade effluent consent from Northern Ireland Water.
Use the correct drainage system
You can take simple measures to use the right drainage system:
- Draw up a drainage plan to identify all drains and update it after building work. If you do not have the expertise in-house, use a reputable drainage business to do the work for you.
- Colour code all manhole covers, drainage grills and gullies. Foul water drains should be painted red, surface water drains blue and combined drainage systems can be marked with a red letter C.
- Check that facilities such as sinks, washing machines, showers and toilets are connected to the public foul sewer or combined drainage system.
If no foul sewer is available, you may be able to use a septic tank or connect to a package sewage treatment plant - download pollution prevention guidelines on the treatment and disposal of sewage where no foul sewer is available (PDF, 245K).
Prevent pollution from high-risk areas
Isolate run-off from refuelling areas from general yard drainage. Cover areas at high risk of contamination, such as refuelling areas, to prevent run-off from rainfall. Where this is not possible you may need to channel run-off to a collection tank.
If your drainage goes to the foul sewer, you may be required to install an oil interceptor. You may need permission from the NIEA or Northern Ireland Water to discharge wastewater from your oil interceptor or other treatment system - download pollution prevention guidelines on the use and design of oil separators in surface water drainage systems (PDF, 79K).
You can only discharge roof water run-off directly to the surface water system if it is clean and uncontaminated. You must ensure that it does not pass through anything that could contaminate it, such as an oil interceptor.