According to current European and ISO standards, groundwater which is to be analysed for metals should be filtered onsite with a 0.45 micron filter. The good news is that at Van Walt we can supply three types:
1. Disc filter 20 cm2 – suitable for very clean water
2. Medium filter 350 cm2 – suitable for medium dirty water
3. High capacity 700 cm2 filter – suitable for dirty water
You will need to decide which filter best meets your requirements but a word of warning: if the water you are testing is dirty and you choose a medium filter you may end up needing more than one filter per well and two 350 cm filters are more expensive than one 700 cm2 filter!
We do not recommend using filters with bailers, even pressurised bailers as adding air under pressure to a water sample to be analysed for metals is not sensible.
You can see how our colleagues at Eijkelkamp Agrisearch in Holland are involved in new Groundwater Standards by downloading the latest issue of their newsletter Geijkt Nieuws from the link below.
Dirk van Walt