Picture two homes for sale within a half mile of each other on the Thornapple River in Ada. One is a ranch built in the 1970s with a private dock and mature trees crowding the bank. The other is a new-construction unit inside Oxbow, the Mosaic Properties development going up along the same river closer to downtown. Both will show beautifully in photos. Both will list at a price that reflects river frontage in one of Kent County's most sought-after zip codes.
Only one of them comes with a system nobody has looked at in fifty years.
That's the part the listing photos never show, and it's the question worth building into an offer before you fall for the view.
Ada runs on wells, not city water
Ada is a township, not a city, and that distinction matters more here than in most West Michigan communities. Kent County's own guidance for residents lists Ada among the townships in the county that rely on private wells rather than a municipal water system, a group that also includes Algoma, Caledonia, Cascade, Grand Rapids Township, Lowell, and several others. If you're used to shopping for homes in Grand Rapids proper or a city with public utilities, this is the first adjustment: on most Ada parcels, especially the older riverfront lots, water comes from a well the current owner installed or inherited, and wastewater goes to a septic system buried somewhere on the property.
That's not a red flag on its own. Private wells and septic systems are common across rural and semi-rural Michigan, and plenty of them function fine for decades. The issue is what you don't know about the specific one you're buying, and how little the state requires anyone to tell you.
Michigan doesn't have one rulebook, it has 45
Michigan is the only state without a statewide sanitary code. Instead, 45 local health departments write and enforce their own rules across the state's 83 counties, which means the protections you'd get buying a well-and-septic property in one county don't automatically apply two counties over. Ottawa County, for instance, requires a septic and water supply evaluation before ownership transfers. Kent County has its own detailed sewage disposal regulations governing how systems are built and maintained, along with a county ordinance establishing inspection and registration requirements for on-site systems, but whether a mandatory evaluation applies to a specific sale depends on the property and the township, not a blanket countywide rule you can assume covers every transaction the way Ottawa County's does.
If you skip this and take "well and septic disclosure" language in a purchase agreement to mean the system has been recently checked, that's a bad assumption to make with the county's largest home price tags on the line.
The system on your riverfront lot may have permits on file. It may not. On older properties, that's a coin flip worth confirming with Kent County's health department before your inspection contingency runs out, not after.
What a failing system actually costs
Here's the number that changes how you should think about your contingency period. A failing septic system can cost more than $20,000 to replace. On a starter home, that's a serious hit. On a Thornapple River property, where waterfront listings in Ada regularly clear seven figures, it's a smaller percentage of the purchase price, but it's still a five-figure surprise that should have been priced into your offer, not discovered three weeks after closing.
With no statewide inspection history and no central database tracking these systems, a buyer on an older river lot may be purchasing a system nobody has evaluated in decades. That's true even on homes that look immaculate above ground. Septic tanks, drain fields, and well casings don't show up in a walkthrough. They show up in an inspection report, if you order one, and if the inspector actually locates and opens the system rather than relying on paperwork that may not exist.
If the seller can't produce a permit, an as-built diagram, or a prior evaluation for a well or septic system on a river property, treat that gap as information, not a formality to skip past.
What new construction actually solves
This is where the contrast between old and new on the same stretch of river gets useful. Oxbow, Mosaic's neighborhood built along the Thornapple River near downtown Ada, sits on infrastructure designed and permitted as part of the platted development rather than something a prior owner installed decades ago. The same logic applies to Fase Street Crossings, where Graystone Homes has been building its Thornapple and Grand floor plans on newly established lots, and to Riverpoint of Ada, the condominium community near the Covered Bridge and Leonard Park. Buyers there aren't inheriting a mystery system. They're buying into infrastructure that was designed, permitted, and inspected as part of construction, with records that exist because the development is recent.
That doesn't make new construction automatically the better financial choice. Legacy river lots often carry larger frontage, mature trees, and a kind of privacy that a platted development can't replicate, and plenty of buyers will pay for exactly that. The point isn't old versus new as a verdict. It's that the price gap between an established river estate and a new-construction unit reflects more than square footage and finishes. Part of what you're paying for, or accepting the risk on, is whether the water and waste systems underneath the house are documented or not.
What to put in your offer
Before you write an offer on any well-and-septic property in Ada, especially anything built before the 1990s, ask for the following:
- The age of the well and septic system, and any permits or as-built diagrams on file with Kent County
- Records of any prior evaluation, water testing, or septic pumping
- Written confirmation from the seller on whether a Time of Sale or Transfer evaluation applies to this specific parcel
- A septic locating service if the system's exact location isn't documented, since damaging an unmarked drain field during a future project is its own expensive mistake
- An inspection contingency period long enough to schedule a well and septic evaluation separately from the general home inspection, since these are typically performed by different specialists
Because Michigan doesn't license well and septic inspectors the way it licenses home inspectors, ask the county health department for its list of approved evaluators for that specific address rather than assuming any general inspector covers this ground.
A few questions buyers keep asking
Does Ada require a septic inspection before a home can sell? Not through a single blanket rule the way some Michigan communities require. Whether an evaluation applies depends on the specific parcel and its history. Confirm directly with Kent County's health department for that address rather than relying on what applied to a different property or a different township.
What if the seller says the well and septic have never had a problem? That's common on older river properties and isn't necessarily reassuring on its own. Time of Sale evaluations in Michigan are generally built to catch systems that are no longer functioning as designed, not just ones that have already caused a visible problem, which means a system can be quietly out of code or nearing the end of its life without ever having triggered a complaint.
Does buying in a new development like Oxbow eliminate this issue entirely? For well and septic specifically, largely yes, since those units connect to systems built and permitted as part of the development rather than something an earlier owner installed decades ago. It's still worth confirming exactly what infrastructure serves your specific building before closing.
Buying on the Thornapple River is still one of the better long-term real estate decisions in West Michigan, and none of this changes that. It just means the smart version of that decision includes a question most buyers don't think to ask until they're already three weeks into a purchase agreement.
If you're weighing an older river estate against something newer in Ada, or you just want a second pair of eyes before your inspection contingency runs out, Brandon Faber can walk through what to ask for and who to call before you're locked into a deadline. Let's Connect.
