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Water quality in boreholes

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7

WQ.184/2019

WRITTEN QUESTION TO THE MINISTER FOR THE ENVIRONMENT

BY SENATOR K.L. MOORE

ANSWER TO BE TABLED ON TUESDAY 30th APRIL 2019

Question

Will the Minister indicate the number of boreholes which are used for residential water consumption; and publish the results of any water-sampling tests undertaken by the Official Analyst, indicating in particular the number of samples tested per year for the past 5 years and the number of results that showed nitrate levels of below 40 mg/l; below 50 mg/l; above 50mg/l; and above 70 mg/l?

Answer

The Water Resources (Jersey) Law 2007 requires that all boreholes and wells used by homes in the Island are registered with the Government of Jersey Environmental Protection team. There are approximately 3393 homes supplied with drinking water by registered or licenced private water supplies (boreholes, wells and surface water)[1].

The Jersey Official Analyst Laboratory has confirmed that the following number of water sample tests have been submitted by households for nitrate analysis in the past 5 years.

 

Year

Total Number of Samples[2]

2014

235

2015

256

2016

269

2017

206

2018

239

2019

107 (up to April 2019)

 

The States of Jersey Official Analyst does not compile an annual breakdown of the specific results, as the results are supplied to the individual householders who commissioned the tests. However, for 2018, the Analyst has provided the following additional specific breakdown in relation to boreholes and wells sampled.

Number of samples

Percentage of samples

Number of samples

Below

Above

Below

Above

40 mg/l

50 mg/l

50 mg/l

70 mg/l

40 mg/l

50 mg/l

50 mg/l

70 mg/l

192[3]

107

123

69

33

56

64

36

17

 

In addition, the Environmental Protection team has previously compiled results from the Official Analyst records between 2008 and 2014.

 

Number of samples

Percentage of samples

Number of samples3 [4]

Below

Above

Below

Above

40 mg/l

50 mg/l

50 mg/l

70 mg/l

40 mg/l

50 mg/l

50 mg/l

70 mg/l

491

226

266

225

134

46

54

46

27

 

Nitrate concentration in groundwater changes gradually over time so the two data sets are broadly comparable.