Ask the seller for the written details
Under the general binding rules, the seller must tell the new owner in writing that a sewage discharge is in place. Ask for this early. It should describe the system and drainage, show where the main parts and the discharge point are, list any changes, and include maintenance details and records where available.
Find out where it drains
This is the big one. A septic tank that drains straight into a ditch, stream or river doesn't meet the rules and will need replacing or upgrading. The guidance says buyer and seller should agree who will do that as a condition of sale.
Check its age and condition
Older brick or single-chamber tanks, cracked lids, signs of leaks, and wet or smelly ground over the drainage field are all warning signs. Ask when it was last emptied and by whom.
Look for the paperwork
Building Regulations completion certificates, the manufacturer's manual, servicing records for a treatment plant, and any environmental permit all help. Missing paperwork isn't always a problem, but it's worth asking about.
Get a survey before you commit
A septic tank or drainage survey tells you what system is there, what condition it's in and whether it's likely to meet the rules. If it needs work, you'll have the facts to negotiate or plan for it.
Want a clear answer for your property?
Tell us what's happening and roughly where you are. No need to know what type of system you have.