Different buildings need different answers.

Two constraints come before water quality

The first is physical. Is there space at the point of entry, a drain within reach, and an outlet on a circuit that will not trip. The second is contractual. Do you own the pipework you want to modify, and does anyone else have to say yes before work starts.

Those two questions rule out more options than any test result does. A tenant cannot fit a softener to a building they do not own. A co-op resident does not control the riser. A restaurant cannot close its kitchen for a day in the middle of service. None of that is about what is in the water.

So these pages start from the building. Each one sets out what is realistic, what needs permission, and which equipment survives those constraints.

It is worth working in that order. Choosing equipment first and discovering the constraint afterwards is how people end up with a quote they cannot proceed with, or worse, a system fitted without the permission that was needed. The building rarely changes to suit the equipment.

Houses

Where you own the property and control the main line, both point-of-entry and point-of-use equipment are available and the decision comes down to what the water actually needs.

• Brownstones and pre-war buildings. Older housing stock across the Northeast often predates the 1986 restriction on lead solder, and many of these buildings still have lead or unknown service lines recorded in municipal inventories.
• Single-family homes on city water. The most flexible case.
• Homes on private wells. No utility tests this water and no report is published.
• New construction. The cheapest point to plan treatment, because the space, drain, and power can be designed in rather than retrofitted.

Shared buildings and rentals

Here the binding constraint is usually permission rather than plumbing, and the timetable is set by a board meeting or a landlord rather than by us.

• Co-ops and condos. In shared buildings the binding constraint is usually approval rather than plumbing.
• Rentals. Anything that does not alter the property is straightforward.

If you rent, these are the filter types that generally need no permanent alteration, and that go with you when you move.

• Reverse osmosis, tankless
• Under-sink carbon filters
• PFAS reduction systems
• Lead reduction filters

Commercial and institutional

In commercial settings the specification is usually driven by equipment protection, throughput, and what the site has to be able to document, rather than by taste.

• Restaurants and cafes. Filtration here protects equipment and carries into the product.
• Offices. Usually a drinking water question rather than a building water question.
• Medical and dental practices. Equipment here has specific feed water requirements, and dental unit waterlines carry their own infection control guidance that filtration supports but does not replace.
• Schools. Lead at drinking outlets is the usual driver, and several states in our area require sampling in school buildings.

Older buildings are their own category

Anything plumbed before 1986 may contain lead solder, and in much of the Northeast the housing stock predates that by a long way. In those properties the highest-value intervention is usually the cheapest one: a filter certified under NSF/ANSI 53 for lead at the tap you drink from, rather than a far more expensive system at the main line that sits upstream of where the lead enters.

Municipal service line inventories are now published, so you can often check the recorded material for your own address before spending anything. An entry of unknown is a prompt to test rather than a reassurance.

Getting the approval conversation right

Vague requests get refused more often than specific ones. Where you need a landlord or a board to agree to work, the proposal that tends to succeed states the equipment, confirms a licensed contractor will fit it, carries evidence of insurance, and commits to removing it and making good at the end of the tenancy.

We can supply the written scope and the insurance certificates for that submission. It is worth starting before booking any work, because several weeks is normal and some boards meet only monthly.

When the problem is the building's rather than yours

Some water complaints cannot be solved from inside a single unit. Discoloured water throughout a building after work on the mains, low pressure confined to upper floors, or a smell affecting several apartments at once are building-level issues. Filtering one kitchen tap treats a symptom while the cause continues.

Taller buildings often feed from a shared storage tank, and those carry their own cleaning and maintenance obligations. A tank that has not been serviced is a matter for the managing agent rather than for a resident buying equipment.

We will tell you when that is what we are looking at. Raising it in writing with the agent or the board is more likely to fix it than anything we could install, and we would rather say so than sell a filter that cannot reach the cause.