Installation service
Under-sink reverse osmosis installation
Installation of a reverse osmosis system in the sink cabinet, with a dedicated tap and a drain saddle or air gap connection as the local code requires.
The cabinet survey that prevents surprises
Under-sink reverse osmosis is a straightforward job in a cabinet with room and an awkward one in a cabinet without it. A tank system needs space for the membrane housing, the pre-filters and post-filter, and a storage tank roughly fifteen inches tall standing upright.
We check for an accessible cold water shutoff, because teeing into the supply needs one and the valve under many older sinks is the first thing to fail.
We also check what else lives in that cabinet. A waste disposal unit, a boiling water tap, or a water softener bypass can all take the space the tank needs, and a tankless system is often the better answer in that situation.
The tap and the drain connection
Most systems feed a dedicated tap, which needs a hole in the sink or worktop. Some sinks have a blanked spare hole from the factory. Where they do not, we drill, and the material decides how straightforward that is. Stainless steel and composite are routine. Granite and quartz need a diamond core and more care, and we will quote that separately rather than discovering it on the day.
The drain connection carries the concentrate stream. Local codes differ on what is acceptable: a saddle clamp on the waste pipe in some jurisdictions, an air gap fitting at the sink deck in others. An air gap is more visible and occasionally gurgles, and where the code requires it there is no choice about that.
If drilling the worktop is not acceptable, either because you rent or because you do not want a second tap, a countertop tankless unit avoids it entirely.
Commissioning, and why the first tank is discarded
A new membrane and new carbon cartridges carry preservative and manufacturing residue. The first full tank is flushed to drain rather than used, and on some systems the first two.
We set the storage tank pressure with a gauge while it is empty, because a tank at the wrong pre-charge either delivers a trickle or holds far less water than it should. This is the commissioning step most often skipped, and it is the usual reason a new system disappoints on flow.
Then we check for leaks under working pressure, leave the system running, and come back to the fittings before we finish, since compression joints occasionally need a further quarter turn once they have settled.
What we need in place
These are checked at the survey rather than discovered on the day. Where something is missing it changes the scope, and we would rather price that honestly up front.
- An accessible cold water shutoff under the sink
- Cabinet space for the unit and, on tank models, the storage tank
- A drain connection point
- A spare hole in the sink or worktop for the tap, or permission to drill one
Typical duration. 2 to 4 hours
Permits and local rules
Some jurisdictions require an air gap rather than a drain saddle. We fit to whichever the local code specifies.
Equipment this covers
- Reverse osmosis, tank. A membrane system under the sink that produces treated water to a dedicated tap and stores it in a small pressure tank.
- Reverse osmosis, tankless. A pumped membrane system that produces water on demand rather than storing it, so it takes far less cabinet space and can sit on a counter.
- PFAS reduction systems. Reverse osmosis or a certified activated carbon system aimed at per- and polyfluoroalkyl substances.
- Lead reduction filters. Point-of-use filters certified for lead under NSF/ANSI 53.
Problems this service is usually booked for
Common questions
Do you have to drill my worktop?
Only if the system feeds a dedicated tap and there is no spare hole already. Many sinks have a blanked factory hole that can be used. Stainless steel and composite are routine to drill. Granite and quartz need a diamond core and more care, so we quote that separately rather than discovering it on the day. If drilling is not acceptable, a countertop tankless unit avoids the question entirely.
Why is the first tank of water thrown away?
New membranes and carbon cartridges carry preservative and manufacturing residue, so the first full tank is flushed to drain rather than used, and on some systems the first two. It is a commissioning step rather than a sign of a problem. We do this before we leave, so the water is ready to use when we hand over.
The flow from my existing RO tap is weak. Is the membrane dead?
Usually not. The most common cause is a storage tank that has lost its air pre-charge or become waterlogged, and that presents exactly like a failing membrane. Checking and resetting tank pressure takes minutes and is part of any service call. It is also the commissioning step most often skipped on a new install, which is why some systems disappoint from day one.
Other services
- Free water testing
- Whole-house filter installation
- Water softener installation
- Well water treatment installation
- Maintenance and filter replacement
- Repair, any brand
Where we work
We cover New Jersey, Pennsylvania, Connecticut, and New York. Because water quality is a local fact, our service area pages carry the utility, source water, treatment method, and reported contaminants for each town, with the report they came from and the year it covers.
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