I am planning on creating a new setup for Microctenopoma ansorgii and I would like to use rainwater to establish this setup, however I live under the flight path at Gatwick. Do you think this rainwater would be safe to use?
Personally as long as you discard the "first flush" when it rains and filter the rain water will be OK. (google for rain water first flush to see what is required).
There are many ponds, lakes, water ways, nature reserves, water reservoirs (eg Heathrow) all under flight paths and they clearly don't have any issue with water contamination. I regularly walk under the nature reserve under Eastleigh airport approach path and ponds & rivers are teaming with life.
I would watch out for an oily sheen on the water, which may indicate that you are getting un-burnt kerosene from planes taking off.
I use the <"Daphnia bioassay">, it just means that you seed the water butt with Daphnia, and then look to make sure the water you draw off has some <"Daphnia in it">. As long as it does you are good to go.
Thank you all for your replies, I will seed the water butt with Daphnia and see how it goes, failing that I can look at incorporating a first flush system. It's good to know that you have kept killifish successfully in the local area Mike.