Water Treatment Advice

Hello,
I am looking to get a site survey done for a house I'm thinking of buying. House has septic tank and bore water coming from a well which is sunk on the grounds.

I basically need to get a survey done that will let me know if the current set up is safe and within regulations. I tried to get a list of authorised surveyors from the planning office but they dont have one!! I checked few resources Water Treatment Video for more information but did not find much.
Has anyone got any info / lists of companies or individulas who do this kind of work?
Survey specifically for the water / septic tank - engineers rep. already done for house.