The list points out what lab tests can be performed on the water sample.
a.- Bacteriological.
b.- Physicochemical.
c.- Chemical.

In the chemical group of tests, two correspond to pesticides. They are PCBs (pentachlorobiphenyls) and Organotin derivatives (esters, normally methyl).

Organo tin pesticides are new class of pesticides that are used frequently. The problem with them is that they pass into the water thus contaminating it. Organo tin esters are very dangerous if consumed.

Several counties around the world, control organo tin esters in water for human consumtion. EPA is behind all efforts.

See,
http://books.google.com.uy/books?id=sW2qBgXqlaQC&pg=PA465&lp...
Tin can be methylated in the environment to form organotin species,

http://www.iso.org/iso/catalogue_detail.htm?csnumber=31362
ISO 17353:2004 specifies a method for the identification and quantification of monobutyltin, dibutyltin, tributyltin, tetrabutyltin, monooctyltin, dioctyltin, triphenyltin, tricyclohexyltin compounds and/or cations in drinking water, surface water and wastewater containing not more than 2 g/l of suspended material. The working range is 10 ng/l to 1 000 ng/l. The respective anions are not determined.