Customer’s property is for business use only

The example below is based on a Water Quality Notice from 10 July 2015 to 3 October 2015, but the calculation process will be the same for any dates.  

In this example, the closest meter reading to the start date of the Water Quality Notice was a reading of 210 on 1 July 2015 and the closest meter reading to the end date of the Water Quality Notice was 340 on 31 October 2015.

The tariff discount is calculated using the following steps:

  • The water usage between the two reads was 340-210 = 130m³ over 123 days (1 July 2015 to 31 October 2015)
  • Based on this usage an average daily usage over the read period is calculated as 130/123 = 1.0569m³ per day
  • The Water Quality Notice period ran for 86 days (10 July 2015 to 3 October 2015)
  • Using the average daily usage calculated above, the water usage over the Water Quality Notice period is 86*1.0569m³ = 90.893m³
  • If the water supplied rate used for billing was €1.1 per 1m³ the Water Quality Notice period usage charge is 90.893m³*1.1= €99.98
  • The next step in the calculation is to apply the discount percentage to this water usage value
    • Customers who use more than 50,000m³ of water per annum and are not involved in the manufacture or production of food and drink will receive a 5% water tariff discount
    • All other customers will receive a 40% water tariff discount.
  • If, in this example, the customer uses less than 50,000m³ of water per annum, the Water Quality Discount will be 40%
  • The tariff discount due to the customer is €99.98*0.4 = €39.99

In this example, the tariff discount is for a Water Quality Notice that closed prior to 20 November 2018 and so would be applied as a one-off adjustment to the bill. If the Water Quality Notice dates are after 20 November 2018, the calculation would be the same, but the tariff discount would be applied to each bill for the days impacted within that billing period, until the Water Quality Notice is lifted.

Customer’s property is for business and domestic use

The calculation below is based on the same information as used for a customer whose property is used only for business use with the only difference being that the customer also receives a domestic allowance of 50m³ per annum. 

The Water Quality Notice was in place from 10 July 2015 to 3 October 2015. The closest meter reading to the start date of the Water Quality Notice was a reading of 210 on 1 July 2015 and the closest meter reading to the end date of the Water Quality Notice was 340 on 31 October 2015.

The tariff discount is calculated as follows: 

  • The Water Quality Notice period usage charge is calculated in the same way as the previous example and is €99.98 (shown for reference below):
    • The water usage between the 2 reads was 340-210 = 130m³ over 123 days (1 July 2015 to 31 October 2015)
    • Based on this usage an average daily usage over the read period is calculated as 130/123 = 1.0569m³ per day
    • The Water Quality Notice period ran for 86 days (10 July 2015 to 3 October 2015)
    • Using the average daily usage calculated above, the water usage over the Water Quality Notice period is 86*1.0569m³ = 90.893m³
    • If the water supplied rate used for billing was €1.1 per 1m³ the Water Quality Notice period usage charge is 90.893m³*1.1= €99.98
  • Prior to applying the discount percentage, the Water Quality Notice period usage charge is adjusted for the domestic allowance received by the customer for the Water Quality Notice period. In this example the domestic allowance for the Water Quality Notice would be calculated as follows:
    • The annual domestic allowance is 50m³
    • The daily domestic allowance is 50/365 = 0.13703
    • The domestic allowance for the Water Quality Notice period is 0.1370*86 = 11.78m³
    • If the water supplied rate used for billing was €1.1 per 1m³ the Water Quality Notice period domestic usage charge is 11.78m³*1.1= €12.96
  • The domestic allowance for the Water Quality Notice period is then deducted from the water usage charge for the Water Quality Notice period, to give the revised water usage charge that the discount percentage is applied to. So in this case the revised water usage charge is €99.98 - €12.96 = €87.02
  • If, in this example, the customer uses less than 50,000m³ of water per annum, the Water Quality Discount will be 40%
  • The tariff discount due to the customer is €87.02*0.4 = €34.81

If in the above example the domestic allowance had been 400m³ and not 50m³ the domestic allowance for the Water Quality Notice period (using the same methodology as above) would be €103.67. The resulting revised usage charge is negative and so in this case no tariff discount would be due to the customer.

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