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 isn’t 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 microgram 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 mictogram 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 microgram per litre
trichloroethylene 0.1  
trifluralin 0.01  
triphenyltin compounds 0.001  
xylenes 3 o-xylene and m/p-xylene each to 3 micgrograms 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.