Guide
Buying a filter online or hiring an installer
Where online purchases go wrong, which jobs are genuinely do-it-yourself, and what an installer is actually for.
Buying online is often the right call
We fit equipment customers bought themselves, and we are not going to pretend that is a mistake. For a straightforward under-sink carbon filter on accessible plumbing, buying online and fitting it yourself is sensible and it saves real money.
What goes wrong is not usually the decision to buy online. It is buying the wrong thing, because product listings in this category are written to imply coverage that the certification does not support.
Send us a model number before you buy, or before you book a fitting, and we will tell you what it is actually certified for. That check is free and it takes a few minutes.
The three ways online purchases go wrong
Certification language. A filter certified under NSF/ANSI 42 is tested for taste and odour, essentially chlorine. It is not tested for lead. Lead is standard 53. PFAS is 53 or the P473 protocol. A listing claiming to reduce contaminants without naming the standard and the specific contaminant has told you nothing you can verify.
Flow rate. A filter rated below your property's demand causes a pressure drop that shows up as a weak shower whenever another fixture runs. The rating is on the datasheet rather than the headline.
Consumables. A cheap unit using proprietary cartridges can cost considerably more over five years than a more expensive one taking standard sizes. Work out the five year cost before comparing purchase prices.
Which jobs are realistic to do yourself
Genuinely straightforward: faucet-mount filters, countertop units, filter jugs, and replacing cartridges in an existing system. Most people change an under-sink cartridge in about ten minutes.
Reasonable with care and basic tools: an under-sink carbon filter on accessible plumbing with a working shutoff valve, as long as you are comfortable making compression connections and pressure testing them.
Worth thinking hard about: under-sink reverse osmosis, because of the drain connection, the local code position on air gaps, and the commissioning steps. Tank pre-charge in particular is the step most often skipped, and it is the usual reason a new system disappoints on flow.
Not do-it-yourself: anything on the main line, anything requiring a permit, softener installation with a brine drain, ultraviolet on a well with a known bacteria problem, and any well treatment train.
What you are actually paying an installer for
Specification, more than labour. Matching equipment to a test result, sizing it for your flow and household, and getting the stage order right on a multi-stage system.
Code compliance. Whether your jurisdiction requires an air gap rather than a drain saddle, whether a permit is needed on the main line, and whether brine discharge to the sewer is restricted where you live.
Commissioning. Flushing media, setting tank pressure with a gauge, pressure testing under working conditions, and returning to the fittings once they have settled.
Someone to call. If a joint we made weeps in six months, that is ours. If a joint you made weeps in six months, it is a Saturday.
Questions worth asking any installer
Which NSF/ANSI standard is this model certified to, and for which specific contaminant.
What did the test show, and can I have the results in writing.
What will this equipment not fix.
What do replacement cartridges cost, what are the part numbers, and can I buy them myself.
Is a permit required at this address, and who pulls it.
What exactly is covered by your warranty as opposed to the manufacturer's.
An installer who cannot answer the first and third of those is selling rather than specifying.
Common questions
Will you fit a filter I bought from someone else?
Yes, at the same standard as anything we supply, including commissioning and the replacement schedule. Send the model number first so we can check what it is certified for and whether it suits your plumbing. What we cannot do is warrant the equipment itself, which remains the manufacturer's responsibility.
Does self-installing void the manufacturer warranty?
It depends on the manufacturer, and some do require professional installation for their cover to hold. Read the warranty terms before you start rather than after. That requirement is a common reason people buy online and then call us to fit it, and we provide written confirmation of the work for that purpose.
The kit did not include the right fittings. Is that normal?
Very common. Online kits are built for a generic installation and frequently omit the adaptors needed for a specific pipe material or an unusual shutoff valve. Identify what is missing before you close the water off, because discovering it mid-job with the supply isolated is the worst possible time.
Related reading
- water filter installation: install your own filter
- water filters: under sink carbon
- guides: water filter installation cost
Other guides
Next step