You should make arrangements for your seller to get a few estimates from some local reputable septic companies...the septic company in keeping with the town codes will make recommendations....there are variables...a larger tank may require additional leeching field, maybe not...the experts will let you know...if the soil is good/sandy that's helpful, if your client's home is on rock...Blasting time! Best case scenario 2,500 for just a tank...very worst case scenario, you are on rock, need blasting and top fill...25,000..Most upgrades for me have been fortunately under $10,000. BTW If the land can sustain a larger house...and the difference in dollar amnt for a 4BR septic vs 5BR septic is small, go larger!
Best of Luck,
Lisa Jones, Higgins Group... more