I am currently trying to buy a house in the country. The current septic tank is on the neighbor's property - so is going to have to be replaced with a system on the legal description of the property. The owners would prefer to install an on-site lagoon. What is the difference between an on-site lagoon and a septic tank and which is preferred? The septic tank is more expensive to install, however, seems much more sanitary to me!!! I can't find info on this ANYWHERE! Please advise!