Does Your ADU Need Separate Utilities in Massachusetts? (Why Every Town Answers Differently)

By Buz Artiano, BuildX | July 2026

Watch: The ADU Loophole Massachusetts Builders Are Just Now Figuring Out

Let's say you've picked a spot in the backyard, and you've got a pretty good idea of how much the project will cost. But now you need to know what the town is going to make you do about water, sewer, and electric. This part catches people off guard quite a bit. Even if you carefully plan your layout and finishes, and get all your financing figured out, you can still end up with some utility issue that could cost you tens of thousands of dollars. The frustrating part is that there is no statewide answer to these types of things. Your town could refuse you a request that someone else you know just got approved for in the next town over.

My name is Buz Artiano, founder of BuildX. We design, permit, and build ADUs all over Massachusetts. However most of our projects are on the South Shore and southeastern Massachusetts. We have put dozens of ADUs in the ground, and our team talks to 25 to 40 families a week who are interested in ADUs. Since January, over 500 families have walked through our home tour, and we are expecting closer to 2,000 this year. The number of people is important because utility rules are all different from one town to the next. Decisions like that are decided by individual water departments, sewer departments, and the electric utility, and the only reason we know them is because we've dealt with utility connections of all types in so many different towns.

Water, sewer, and electric all have their own separate process and rules. Figuring all of them out depends on where you live and which utility company you're dealing with. Two different towns, even if they are right next to each other, can have completely different answers to the same question. But you don't want expensive surprises, so make sure you get answers from every department before you make a budget. We walk all of our clients through this and show them how to tell a basic utility connection from an expensive one.

So Does Your ADU Need Its Own Utilities?

There's no statewide rule that says yes or no. The right to build the ADU is what comes from the state itself. The utility connection rules come from your town's water and sewer departments and from the electric company, and they don't coordinate with each other at all. When you build an ADU, your water company can tell you that you have to run a completely separate service, and then your sewer department can refuse a new street connection, and the electric company could limit you to one service for the whole property. All of these are separate decisions made by different companies, which is why the answer to whether your ADU needs separate utilities depends on which town you live in. The rest comes down to what each department requires and what it costs when a lot of site work has to be done.

Why Does Every Town Give You a Different Answer?

Massachusetts made ADUs allowed by right when they voted in the Affordable Homes Act. What that means is that a qualifying ADU doesn't need a special permit or approval from the zoning board. You can read all the details on that if you go to mass.gov. But the state has nothing to do with how you connect water, sewer, and electric. All of that is determined by the local departments.

That's why two towns can look at the same project and have different answers on how to connect the utilities. Maybe a water superintendent in one town has had bad experiences with shared meters, so they tell you that you have to run separate service to the ADU. Another town says they don't want anyone tearing up the street to make a new connection, so they say the ADU has to share the existing service. Either way of doing it is fine with the state, they let the utility companies make those decisions. When we quote a project, the utility connections are a variable that we need to get a firm answer on at the beginning, because it can change the budget by tens of thousands of dollars.

What Are the Rules for Water Service?

Water tends to be the least predictable of them all. Every water department treats an ADU differently, and there is no discernable pattern to it, all towns are just different. Some say you have to install a separate water service with its own meter for the ADU. Others explicitly prohibit adding a separate service and meter and they make you come off the back side of the existing meter, running the ADU's supply from the primary house. And then some of them will let you do either.

What the utility companies care about is how much it's going to cost and how bad the disruption will be. A separate service can mean they have to run a new tap and a trench from the water main in the street, which tears the road up and costs a lot of money. But running off the existing meter means that all the disruption stays on your property without turning the street into a construction zone. In some towns, if we just nicely point out the state's published ADU rules, they'll let us just pull water from the main house instead of trenching a separate line to the street. The only way to get an answer to this however, is to ask the water department directly, in writing, before you design the connection.

How Do Towns Handle Sewer Connections?

When we do projects where the property is on public sewer, there's more of a pattern than there is with the water companies, and it's pretty much decided by the towns not wanting to have to tear up the road. In the towns where we connect to public sewer, they want the ADU tied into your existing line before it reaches the street. Basically that means we install a wye fitting that lets the ADU's waste line just feed into the main house's line, you just have to make sure you have a clean-out for future access, somewhere in the front yard rather than out at the street.

That's because the pipes under many Massachusetts roads are very old, and the town would rather you dig up your own front yard and make the connection there than tear up fragile and aging pipes under the street. For you, a yard connection avoids road work, and road work can cost you a fortune. There is an exception, that's if your existing line isn't able to take a new connection where waste flows downhill into the pipe on its own. Another exception is if your only route runs out toward the street. That's when it starts to get expensive.

Can You Get a Separate Electric Meter for Your ADU?

Electric is where we get the least pushback when it comes to separate metering, but there is a constraint here. In our part of Massachusetts, the electric utility is Eversource, and Eversource only lets you have one service per property. That's an Eversource policy, not a state law, but it's why we have to do a separate ADU meter in a very certain way. If the ADU is built in a spot where a line can't reach it, you can't just do a second service drop to the new building.

Instead, the main line stays at the main house, and we just put in a 400-amp, two-meter setup. The service from the main house is enough to power both homes, so we split it into two separate meters at the main house. One goes to the main home and the other goes to the ADU, so each home gets a separate bill on its own account. When the layout of the property allows it, we can put up another pole and wire the ADU from that.

We plan out the electrical connection before we give a price, because the one-service rule changes things in ways that most people don't realize. Making sure you have ample primary service to power two homes isn't the same thing as running two regular service lines, and it also changes how the panel is set up, it changes the meter setup, and the trenching that has to be done. We confirm the power company's rules and the ADU's distance from the existing service at the very beginning, because it decides whether you are looking at a basic two-meter setup or if you're stuck with the cost of setting another pole. People don't usually think to ask about it, but it's one of the most important details that can either make or break your build.

What Could Send Your Utility Costs Through the Roof?

So we've noticed a pattern here. The cost of getting utilities to your ADU has less to do with the unit itself and more to do with how far you have to reach and whose ground you will be tearing up. There's a few things that can make things get expensive fast. The first is any work that requires tearing up the street. Installing a separate water tap, a new sewer connection at the road, or power out to the main all mean there will be trenching, restoration, and permits involved. The second thing is if you live on a state road. If your frontage road is on a Massachusetts Department of Transportation right-of-way, the state's control of the road surface, you may have to use a controlled low-strength material when you backfill the trenches. They also have stricter restoration standards and a slower approval, and all of that makes the price go up fast. The third thing that can cost you a lot is a town that has decided to make utilities and access difficult on purpose. As of mid-2026, we have one town on the South Shore that requires you to share both water and sewer with the main house and has recently said they won't allow a separate driveway for the ADU either. We've had other towns require a special permit from the zoning board just to add a second driveway.

When several of these conditions add up, it can cause utility connections to add $20,000 to $30,000 to the project. None of that shows up in your basic per-square-foot estimate, which is exactly why you have to plan for it before you get set on a price or a budget.

When Do Separate Utilities Actually Make Sense?

We build ADUs with all different types of utility connections and a lot of times doing them all separate is the best way to do it, but not always. That's because separate is not always better and it's usually more expensive. If you're building for a parent and the ADU is going to stay in the family, then sharing utilities with the main house is simpler, cheaper, and works just fine. The unit works the same day to day whether it has its own water meter or whether it runs off the main house.

Separate utilities are worth the extra money when you want the ADU to be its separate home that isn't tied to the main house at all. If there's any chance you'll ever turn the ADU into a condo and sell it, then having separate water, sewer, and electric make that easy because both homes are already billed separately on their own accounts. You can only turn an ADU into a condo if you already have the utilities installed separately. So it's not about how you get separate utilities, it's about whether you ever want to sell the ADU on its own, and whether you want to plan for that now. Give it some thought, so you know that what you decide will work for you long term.

Get Your Town's Answer Before You Price the Build

Utilities are the biggest things that can increase an ADU budget after the fact, but you can get all the answers if you just find out early in the process. Water depends on your town's policy on separate versus shared service, sewer depends on whether you can tie in before the street, and electric depends on your utility's one-service rule and where the ADU is built. Confirm all three for your specific property so you can put together a reliable budget, instead of one that changes once you have all the information later on.