Northern Ireland Water (NI Water) is responsible for supplying water and sewerage services to businesses and charging for those services. These charges are determined by either metered or unmeasured means.

Metered water charges for businesses

If you have business premises with a water meter you will pay measured charges based on the size of your supply pipe, and a variable charge based on the amount of water used.

Unmeasured water charges for businesses

If you do not have a water meter, you will pay unmeasured charges. This will be added to a variable charge based on the rateable value of the property.

Domestic allowance for eligible metered water customers

If you pay business rates, you may be entitled to a domestic allowance of 100m3 every six months. The domestic allowance is subtracted from the amount recorded on the water meter. It is worked out for the exact number of days covered by the bill. Any unused portion of the allowance cannot be carried forward into a new bill period. Customers wishing to apply for the domestic allowance should contact NI Water. Proof of your rateable status may be required to confirm eligibility. 

Read further details on understanding your bill and NI Water's charges.

Assessed charges for water

Where it has not been possible to install a water meter, you can request an alternative assessed charge for water and sewerage. The assessed charge includes two elements: a standing charge and a variable charge based on the loading units attributed to the water-using appliances on your property. You can apply for a domestic allowance against assessed charges if you pay rates.

By reducing the amount of water your business uses you can lower your water and sewerage costs. See reduce your water, sewerage, and effluent costs. Water saving tips for businesses.

Large user tariff

You may be eligible for a large user tariff. This can mean paying a lower rate to reflect the lower costs of serving large users. NI Water can tell you if your business qualifies for large-user tariffs.

Who regulates the water industry?

The Utility Regulator is the regulator for the water and sewerage industry in Northern Ireland. The Utility Regulator sets limits on increases in water and sewerage companies' charges. They monitor investment, levels of service, and companies' compliance with relevant legislation and conditions of appointment.

Water from non-mains sources

If you use water from a non-mains source such as a well, borehole, or reservoir you may need to apply to abstract or impound water from the Northern Ireland Environment Agency.

If you use of water from a non-mains source, either as the main or additional supply source, you must tell NI Water. This means your sewerage charges can be worked out correctly.

Businesses must pay charges for foul sewerage and drainage. Sewerage charges have two elements:

• a standing charge
• a variable charge

Measured charges for sewerage

For customers billed on measured charges, the variable charges are based on the amount of water used with an allowance for water which does not return to the sewer. Standing charges are added based on the size of their water supply pipe. The standard non-return to sewer allowance is 5%. Businesses that can show a higher non-return to sewer can apply for a different allowance.

Domestic allowance for measured sewerage customer

If you pay business rates, you may be able to apply for a domestic allowance of 95m³ every six months. This allowance is subtracted from the volume recorded on the meter. It is worked out for the exact number of days covered by the bill. Customers wishing to apply for the domestic allowance should contact NI Water. Proof of your rateable status may be required to confirm eligibility.

Read further details on understanding your bill and NI Water's charges.

Unmeasured charges for sewerage

For unmeasured customers, the variable element is based on the rateable value of the property with a standard rate standing charge.

Assessed charges for sewerage

Where it has not been possible to install a water meter, you can request an alternative assessed charge for water and sewerage. The assessed charge includes two elements: a standing charge and a variable charge based on the loading units attributed to the water-using appliances on your property. You can apply for a domestic allowance against assessed charges if you pay rates.

By reducing the amount of water your business uses you can lower your water and sewerage costs. See reduce your water, sewerage, and effluent costs. Water saving tips for businesses.

If you want to discharge anything other than clean water into surface water drains or watercourses you should check whether you need permission from the Northern Ireland Environment Agency. See preventing water pollution.

Trade effluent is any liquid waste that is produced by any trade or industry process at trade premises. It does not include wastewater that is considered to be domestic sewage. Domestic sewage is charged separately. Trade effluent includes waste water contaminated with:

What constitutes trade effluent?

Trade effluent includes waste water contaminated with:

• fats, oils, and greases
• chemicals
• detergents
• heavy metal rinses
• solids
• food waste

Northern Ireland Water (NI Water) will charge according to the amount and strength of effluent before it is discharged into the sewers. Trade effluent charges.

You must have the consent of NI Water before you discharging trade effluent into public sewers.

Your business may receive a number of bills relating to water and wastewater charges.

Water bills

Factors that affect your water bill charges include:

• size/diameter of the incoming water supply pipe
• year - unit costs are reviewed annually
• the demand placed on the service either through usage or wastage

Metered charges

For customers with a meter, the bill will show the charge based on the volume of water used. A standing charge will be added based on the size of your water supply pipe. When you receive a bill, check the meter serial number to make sure you are being billed for your meter. Measured charges.

Unmeasured charges

Bills may be based on 'estimated', 'actual', or 'read' meter readings. NI Water charge for all water supplied and recorded through the meter, whether used or lost through leakage. Leakage, allowances and costs.

Sewerage charges may appear on your trade effluent bill rather than your mains water bill.

For customers without a meter, the bill will show the charge based on the rateable value of the property and a fixed fee standing charge. Unmeasured charges.

Sewerage bills

Sewerage (domestic wastewater) charges appear on either your water bill or your trade effluent bill and can be based on:

• incoming water less non-return to sewer allowance
• incoming water less measured trade effluent volume, less non-return to sewer allowance
• the rateable value of your premises

If your bill is higher than normal because of a leak, you may be eligible to apply for an adjustment of the sewerage charges on your bill if the leaked water did not return to the sewer.

Trade effluent bills

Trade effluent volume may be metered or based on the calculation of water use, less non-return to sewer allowances. These allowances include losses, eg from non-recovered steam, evaporative losses from cooling towers, and water used as a product ingredient.

To calculate the amount discharged as domestic sewerage, you may be asked to provide data.

Trade effluent charges are based on the Mogden Formula that relates cost to the volume and strength of the trade effluent discharged. The formula takes into account the facilities at the sewage treatment works that treat your trade effluent.

You can limit the environmental impact of your business by reducing the amount of water you use. Since Northern Ireland Water will charge both to supply water and to take it away, cutting the amount you use also helps to reduce your costs.

How to reduce water consumption

To limit your water consumption, make sure that you:

• check the supply pipe is the appropriate size for your needs
• check meter readings and monitor bills regularly
• check pipes for leaks, especially in cold weather
• purchase water-efficient equipment

The type of measures you could consider to reduce your water use will depend on the type of activities that your business carries out.

Office-based businesses can fit washroom devices such as push taps, spray taps, cistern displacement blocks, sensor flushing controls, etc. See save water at commercial premises .

Industrial businesses may be able to reuse process water or grey water from washing and cleaning equipment, or investigate non-mains water sources, eg rainwater. Save water at industrial premises.

Sewage and trade effluent

The costs to businesses of having their sewage and trade effluent treated can be significantly higher than the cost of the incoming water.

You can reduce wastewater costs in a number of ways:

• reduce the overall amount of wastewater you generate
• reduce the strength of any trade effluent you produce
• reuse wastewater wherever possible