In reply to Mattyk: Septic tanks do drain... are you certain that what you are looking at is not the perfectly legitimate soakaway connected to a tank?
The normal set up is a tank that captures and (possibly) part treats the solids via microbial action (in general treatement is limited as soaps bleaches etc tend to kill off the microbes these days). Holding capacity a few thousand litres. Grey water fluid then drains out of that through pipework into a soakaway which may or may not be on your property (usually consents/details etc are in the title deeds). No domestic tank will hold enough to not have drainage into a soakaway. You get the tank de-slugged every year or two at your own expense (your water rates are however reduced) to remove accumulated solids and improve hodng capacity and thefore duration that material spends inside the tank before it drains out.
If thats what you have its potentially fine, consents and possibly SEPA approval should be on file and your obligation is to make sure it works and doesn't discharge 'nuisance' material (i.e. untreated solids). If water from roof drainage is also piped throuh it that may cause a nuisance by overloading it and causing solids to be washed through too quickly (old wisome was lots of water good as it dilutes things - current wisdom is minimise throughput to increase residence time)... if thats thE case disconnecting rainwater drainage and dealing with that seperately is a good idea
If what you have is effectively a pipe discharging to environment direct its definately not up to scratch but the solution wouLd probably be as already described by another response to dig a hole, insert tank, pipe out of tank underground to roughly where it is already discharging. One assumes the landowner knows and is happy with the discharge therfore there should be no issue improving the quality of what is discharged to the same place.
I'm not familiar with genuine reed bed type set ups but they are also a possibility and that may be what you have - an old version that could be brought up to scratch if required.... my understanding of these is that they are pretty much as they sound, discharg into a pond of some type with plants to treat and a slow release of cleaner water eventually.
Sellers agent should be able to get the answer to what system is in place, what consents exist etc, possibly what maintenance has been done (if your lucky!) and then its a cost/risk/benefit decision for you whether to bid and how much to factor in for potential improvements.
