A whole house water filter in San Diego treats the water where it enters the home, so every tap, shower and appliance gets the same filtered water. This page covers what a filter on the main line can and cannot do, the standards to ask about, and how it fits with a softener.
Water Softener San Diego is an independent referral service, not an installer, plumber or equipment seller. When you send the form, your details are passed to an independent local water treatment pro, who can contact you and prepare a quote.
What a whole-house filter is
A whole-house filter is a point-of-entry system: one or more filter housings or tanks fitted on the main line after the water meter and shutoff, before the water branches to the water heater and the rooms. A point-of-use filter, by contrast, treats one tap. The whole-house filter treats everything the house uses, which is why it is chosen for taste and odor at the shower as well as the sink.
- Cartridge housings: one or more filter cartridges in canisters on the line
- Media tanks: a larger tank of filter media that backwashes to a drain
- Combined systems: a filter stage ahead of or after a softener
What it can and cannot do
What a whole-house filter reduces depends entirely on what it is built and certified for. This site does not quote performance numbers for any filter type. The way to judge one is the certification: the NSF/ANSI standard and the list of contaminants under it.
| Concern | Standard to ask about | Notes |
|---|---|---|
| Chlorine taste and odor | NSF/ANSI 42 | Aesthetic effects; ask what disinfectant it is certified to reduce |
| Lead and other health contaminants | NSF/ANSI 53 | Check the contaminants named on the certification |
| Incidental contaminants | NSF/ANSI 401 | A separate list; ask which ones |
| Hardness, spots and scale | NSF/ANSI 44 (a softener) | A filter does not remove hardness |
| Iron or manganese staining | Ask after a water test | EPA guidelines are 0.3 and 0.05 mg/L |
The one thing a whole-house filter does not do is soften. The City of San Diego says its water typically averages about 16 grains per gallon, ranging from 16 to 18 by area and demand. That hardness is dissolved calcium and magnesium, and removing it is a softener’s job. If spots and scale are the problem, start with the San Diego hard water guide or the water softener installation page.
Pairing a whole-house filter with a softener
A home that wants filtered water at every tap may also want soft water, and the two can be fitted together on the main line. The order of the equipment depends on what each part is meant to do, and the installer decides it from the water test and the maker’s instructions. Ask the installer to explain the order they propose and why.
If you also want water for drinking that is filtered further, an under-sink reverse osmosis system at the kitchen tap is one addition to consider. EPA says point-of-use RO can potentially remove contaminants such as lead, PFAS and arsenic, and NSF/ANSI 58 is the standard for it.
Whole-house reverse osmosis
Reverse osmosis for the whole house exists, but it is a bigger installation than an under-sink unit. The installer sizes it after a water test. If someone proposes whole-house RO, ask what it adds over a whole-house filter and an under-sink RO unit together, and how much water it sends to the drain.
Want filtered water at every tap? Tell us about your home and a local pro can contact you about a quote.
Sizing for flow
A whole-house filter has to pass all the water the house uses at once: a shower, the washing machine and a kitchen tap running together. A filter that is too small for that flow lowers the water pressure. The installer sizes the housing, cartridge or tank to your home’s peak demand and the size of your main line, and should be able to tell you the flow rating of what they propose.
- The number of bathrooms and people in the house
- The size of the main line
- Whether a softener or other equipment is on the same line
- Room on the main line, and access for cartridge changes
Where it goes in a San Diego home
The filter goes on the main line after it enters the house. Depending on the home, that can be in a garage, at a side wall or in a utility closet. Ask whether the outside hose bibs and the irrigation line will be on filtered water: where the plumbing allows, some owners keep the garden on the line before the filter so the cartridges are not spent on watering. A bypass valve lets the house keep water while a cartridge is changed.
Whole-house filter or under-sink filter?
The choice comes down to where you want filtered water. If you care about taste and odor at the shower, the bathroom sinks and the washing machine as well as the kitchen, a whole-house filter is the way to get it, because it treats the water once for the house. If you care about the water you drink and cook with, an under-sink filter or RO at the kitchen tap treats a much smaller volume and can be chosen for specific contaminants.
| Whole-house filter | Under-sink filter or RO | |
|---|---|---|
| Where it treats | Every tap, shower and appliance | One kitchen tap |
| What it suits | Taste and odor everywhere | Drinking and cooking water |
| Standards to ask about | NSF/ANSI 42, 53, 401 as certified | NSF/ANSI 42, 53, or 58 for RO |
| Space needed | A spot on the main line | Room in the kitchen cabinet |
Some owners choose both: a whole-house filter for the general taste of the water, and RO or an under-sink filter at the kitchen for drinking water. Each part is chosen for its own job.
Permits
The City of San Diego lists water softener installations among the minor installations that can get a Simple No-Plan plumbing permit, for properties that are not historically designated. Ask the installer which permit applies to a whole-house filter on your home, and who pulls it. Outside the city, check with that city’s building department.
Upkeep
Cartridges are changed and media tanks are serviced on the maker’s schedule; this site does not set an interval, because it depends on the system and the water. Ask the installer for the schedule in writing and the part numbers of the cartridges, so you can compare the running cost of two systems and not only the first bill.
Questions to ask before you buy
- What do you want this filter to reduce, and is it certified for that under NSF/ANSI 42, 53 or 401?
- What is its flow rating, and is that enough for my house?
- Does it need a drain for backwashing?
- Where will it go, and will the garden be on filtered or unfiltered water?
- How does it work with a softener, and in what order?
- What does upkeep involve, and what does the maker’s schedule say?
For drinking water alone, compare this with the options on the water filtration page. For a plan that covers hardness, taste and anything a test turns up, see water treatment.
What affects the quote
This site prints no prices. The quote moves with the type of filter, the number of stages, the flow rating, whether a softener is fitted at the same time, the piping needed to reach a good spot, and the cartridges or media on the maker’s schedule. A written quote that lists the certification of each part is easier to compare than a single figure.
Questions people ask
Does a whole house water filter soften water?
No. A filter does not remove the calcium and magnesium that make San Diego water hard. A softener does that; the two can be fitted together.
Is a whole house filter worth it in San Diego?
If you want the same filtered water at every tap and shower, yes, it is the way to get it. If you only want filtered drinking water, an under-sink filter or RO at the kitchen tap may be enough.
Will a whole house filter lower my water pressure?
A filter sized too small for the house can. Ask for the flow rating and check it against your home’s demand.
Should the filter go before or after the softener?
It depends on what each part is meant to do. The installer decides the order from your water test and the makers’ instructions.
How often are whole house filter cartridges changed?
On the maker’s schedule. It depends on the system and the water, so ask for the schedule in writing.
Does a whole house filter need a drain or power?
Some do. Media tanks that backwash need a drain, and some control valves need power; cartridge housings may need neither. Ask the installer what the proposed system needs and where it will connect.
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