Guidance

Hazardous substances to groundwater: minimum reporting values

Updated 13 January 2017

The Environment Agency has indicative minimum reporting values (MRVs) for selected hazardous substances in clean water.

Use these values when you carry out a groundwater risk assessment involving hazardous substances.

If the MRV for a hazardous substance is not on this list, you can contact the Environment Agency. The Environment Agency will formulate the MRV for you.

The values are based on environmental permitting guidance for groundwater activities. You can read more about how to assess discernibility of hazardous substances.

In January 2017 UKTAG published a technical report on groundwater hazardous substances. The Environment Agency will consider the report, and incorporate it into current regulatory approaches and guidance if appropriate.

1. Minimum reporting values

Substance	Minimum reporting value (micrograms per litre)	Notes
1,1,1-trichloroethane	0.1
1,1,2-trichloroethane	0.1
1,2-dichloroethane	1
2,4-D ester	0.1	methyl, ethyl, isopropyl, isobutyl and butyl each to 0.1 micrograms per litre
2,4-dichlorophenol	0.1
2-chlorophenol	0.1
4-chloro-3-methylphenol	0.1
aldrin	0.003
atrazine	0.03
azinphos-ethyl	0.02
azinphos-methyl	0.001
benzene	1
cadmium	0.1
carbon tetrachloride	0.1
chlorfenvinphos	0.001
chloroform	0.1
chloronitrotoluenes	1	2,6-CNT; 4,2-CNT; 4,3-CNT; 2,4-CNT; 2,5-CNT each to 1 microgram per litre
PCB (individual congeners)	0.001
demeton	0.05	demeton-s-methyl only
diazinon	0.001
dieldrin	0.003
dimethoate	0.01
endosulfan	0.005	endosulphan a and endosulphan b, each to 0.005 micrograms per litre
endrin	0.003
fenitrothion	0.001
fenthion	0.01
hexachlorobenzene	0.001
hexachlorobutadiene	0.005
hexachlorocyclohexanes	0.001	alpha-HCH, gamma-HCH and delta-HCH each to 0.001 micrograms per litre, beta-HCH to 0.005 micrograms per litre
isodrin	0.003
malathion	0.001
mecoprop	0.04
mercury	0.01
mevinphos	0.005
op DDT	0.002	o = ortho; p = para
pp DDT	0.002
op DDE	0.002
pp DDE	0.002
op TDE	0.002
pp TDE	0.002
parathion	0.01
parathion methyl	0.015
pentachlorophenol	0.1
permethrin	0.001	cis and trans-permethrin both to 0.001 micrograms per litre
simazine	0.03
tetrachloroethylene	0.1
toluene	4
tributyltin compounds	0.001
trichlorobenzene	0.01	135 tcb; 124 tcb; 123 tcb each to 0.01 micrograms per litre
trichloroethylene	0.1
trifluralin	0.01
triphenyltin compounds	0.001
xylenes	3	o-xylene and m/p-xylene each to 3 micrograms per litre. May not be possible to separate m- and p-xylene.

2. List of hazardous substances

On 16 January 2017 the Environment Agency published an updated list of hazardous substances on the JAGDAG (Joint Agencies Groundwater Directive Advisory Group) website.

The Environment Agency will use the updated list of hazardous substances from 16 January 2017 for all new activities that may lead to the discharge of hazardous substances to groundwater.

If your activity has a permit issued before 16 January 2017, the Environment Agency will regulate the activity in line with your existing permit conditions.

The Environment Agency will review all permits in light of the updated list of hazardous substances. These permit reviews will be in line with the existing arrangements for each industry sector. If you want your permit reviewed sooner, you can discuss this with your local site inspector. The permit review may show you need to implement new or amended measures. These measures will be only be required where considered ‘necessary and reasonable’ in accordance with the environmental permitting guidance for groundwater activities.