It depends. ADUs located in existing dwellings with utilities may rely on their existing plumbing (water/sewer) connections. If you propose to modify your existing utilities outside of your house (e.g. upgrade the size of your water line, install a new line, etc.) you will need a permit from DPW&P Engineering. However, ADUs in detached structures will require a permit from DPW&P Engineering as you will need to make changes to the sewer outside of your house and the associated trenching for water and sewer. A plumbing permit will be required to connect the water from the primary dwelling to the ADU. Utility changes to allow ADUs - especially for detached structures require interconnection with your existing utilities and may dictate the location of your new utilities, so it's important to plan for this early in your design process.
We recommend starting this process by contacting DPW&P Engineering to get a copy of your property's sewer connection record by emailing: dpwpermits@worcesterma.gov. Your licensed drainlayer can then Apply for a Permit from DPW&P Engineering for work online.
Note: If you'd like your tenants to pay for their share of utilities, you can ask your licensed contractor to install a sub-meter for you to monitor their usage - but the City will continue to monitor only the existing meter and issue one bill to you as the owner for whatever units are/will be on the property.