It will all depend on what the system was rated for in regards to the bedrooms. This is a great question for your local board of health agent, and depending on what you are building you may have some nice options. All the best
I would double check with your local board of health. Title 5 is a state regulation, but towns have the right to override the process and make the regulation stricter. I have seen many towns allow home owners do just what you are proposing but with 2 conditions. One, the system has to pass the title 5 test (the test result is good for 2 years, or 3 years if the system is pumped on the anniversary date of the initial inspection) And two, the new homeâ€™s bedroom count cannot exceed the existing septic systems capacity. You cannot use the existing septic system to build a 4 bedroom house if the septic is designed to accommodate 3. In that case you would have to expand the septic systems capacity. But, like I said, go to your local board of health to confirm. And best of luck to you!
A passing system does not mean it will meet the needs of a new owner. If two people are selling a house and the new owners will have 6 people, will the system operate as effectively? No one can tell you that from the surface. The components of the system, the age, the past use, the past maintenance schedule, and the inspector can all be important information in determining the future of a septic .
The link below is to the N Reading Health Department page. Best wishes. And when you're on Cape Cod, stop in and say hi. capegroup.com