Full house filtration explained - Plumbers forum 🧰

Date: Fr, 08/09/2024, 10:30 AM | Message # 1

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What common types of full house filtration are available ?

Full house filtration refers to a water filtration system designed to purify water throughout an entire home, rather than just at a single point of use (like a kitchen sink).

These systems typically include several stages of filtration to remove contaminants and improve water quality across all taps and appliances.

Common types of full house filtration systems include:
1. Sediment Filters: Remove large particles like sand, dirt, and rust.
2. Activated Carbon Filters: Eliminate chlorine, volatile organic compounds (VOCs), and improve taste and odor.
3. Reverse Osmosis (RO) Systems: Provide advanced purification by removing dissolved solids, heavy metals, and other contaminants. Some systems include an RO unit as part of a multi-stage process.
4. UV Filters: Use ultraviolet light to kill bacteria and viruses, providing an added layer of safety.
5. Water Softeners: Address hard water issues by removing calcium and magnesium minerals.

George S.

Date: Fr, 08/09/2024, 10:34 AM | Message # 2

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We live in the area with hard water and we can see carbonate deposits on all our appliances.
What would you recommend?

Date: Fr, 08/09/2024, 10:39 AM | Message # 3

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For hard water issues, a water softener would be an effective solution.
It removes minerals that caused hardness and and deposits and sediment on appliances and fixtures.

George S.

Date: Fr, 08/09/2024, 10:42 AM | Message # 4

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How does water softener work ?

Date: Fr, 08/09/2024, 10:52 AM | Message # 5

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A water softener works by using a process called ion exchange to remove hard minerals from the water.

Here’s a simplified overview of how it works:

1. Ion Exchange Process : The water softener contains a tank filled with resin beads that are charged with sodium ions. As hard water flows through the tank, the calcium and magnesium ions in the water are exchanged with the sodium ions on the resin beads.
2. Softened Water : The result is water that has had its hard minerals removed, reducing scale buildup and improving the efficiency of soaps and detergents.
3. Regeneration : Over time, the resin beads become saturated with calcium and magnesium. To restore their effectiveness, the softener undergoes a regeneration cycle. During this cycle, a brine solution (saltwater) is flushed through the resin tank, replacing the calcium and magnesium with sodium ions.
4. Rinsing and Recharging : After the regeneration, the system rinses out the excess brine and is ready to soften water again.

This process helps prevent scale buildup on appliances, pipes, and fixtures, and can extend the lifespan of your plumbing and water-using appliances.

Jane R.

Date: Fr, 08/09/2024, 11:05 AM | Message # 6

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Can I just install reverse osmosis under my kitchen sink, does it worth it ?

Date: Fr, 08/09/2024, 11:15 AM | Message # 7

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Yes, it worth it.
Reverse Osmosis ( RO ) process reduces water contaminants, and even bacteria and viruses that can be found in a tap water.
RO water can be better than water in plastic water bottles.
Once its is properly installed it can last you for decades. the only thing you need to do is to change the filters as prescribed by the manufacturers.

Jane R.

Date: Tu, 07/28/2026, 5:49 AM | Message # 8

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Good to know. Is there a downside to RO systems — I've heard something about them wasting water or stripping out minerals that are actually good for you?

Date: Tu, 07/28/2026, 5:49 AM | Message # 9

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Both of those concerns are legitimate, so let's go through them honestly:

1. Water waste:
This is the most common criticism, and it's true to some extent. Traditional RO systems reject a portion of the water that passes through the membrane as "wastewater" to flush away the contaminants that get filtered out. Older or lower-quality systems can have a ratio of 3-4 gallons wasted for every 1 gallon of purified water produced.

The good news: newer, higher-efficiency RO systems have improved this significantly — many modern units now achieve closer to a 1:1 or 1.5:1 waste ratio, and some even recycle a portion of the reject water back into the pretreatment stage to reduce waste further. If water waste is a concern for you, it's worth specifically asking about the system's efficiency ratio when choosing a unit, rather than assuming all RO systems waste the same amount.

2. Mineral stripping:
This one's also accurate — RO systems remove essentially everything dissolved in the water, including beneficial minerals like calcium and magnesium, not just contaminants. This is a legitimate tradeoff:

On the plus side: you're getting water that's essentially free of dissolved solids, heavy metals, and most contaminants.
On the downside: the water can taste slightly "flat" to some people since minerals contribute to taste, and you do lose some minor dietary mineral intake (though for most people, minerals from food far outweigh what you'd get from tap water anyway).

A common solution: many RO systems now include a remineralization filter as one of the final stages, which adds back a small, controlled amount of beneficial minerals (like calcium and magnesium) after the RO process, improving taste without reintroducing the contaminants that were filtered out.

Bottom line: if you're specifically looking at RO for under-sink drinking water (as opposed to whole-house), I'd recommend looking for a modern, higher-efficiency unit with a remineralization stage — that addresses both concerns you raised without giving up the purification benefits. It's a bit more expensive upfront than a basic RO system, but it resolves the main drawbacks people run into with older or cheaper units.

Date: Mo, 08/10/2026, 3:52 AM | Message # 10

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That's really helpful, thanks. One more thing — since we also have hard water (George mentioned it earlier in this thread and we're in a similar situation), does it make sense to pair a whole-house water softener with the under-sink RO system for drinking water? Or would the softener already make the RO unnecessary?

Date: Mo, 08/10/2026, 3:53 AM | Message # 11

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Good question — pairing them is actually the ideal setup, and they solve two different problems rather than overlapping.
Why they complement each other:

The water softener handles hardness (calcium/magnesium) throughout your entire home — protecting pipes, water heaters, appliances, and fixtures from scale buildup. But it doesn't remove chlorine, VOCs, heavy metals, or other contaminants that might be in your water supply. In fact, softened water actually has slightly higher sodium content, which some people prefer to filter back out for drinking.
The RO system at your kitchen sink handles what the softener doesn't — reducing dissolved solids, chlorine taste/odor, heavy metals, and the added sodium from the softening process — giving you the cleanest possible water specifically for drinking and cooking.

A practical bonus: running softened water into your RO system actually helps the RO unit itself. Hard water minerals can scale up and shorten the lifespan of an RO membrane over time, so pre-softening the water reduces how often you'll need to replace that membrane, on top of the softener protecting the rest of your plumbing.
Bottom line: for a household with hard water, the combination — softener for the whole house, RO under the kitchen sink for drinking water — is one of the more common and effective setups we recommend. Neither one replaces the other; they're solving different parts of the problem, and running them together actually makes both systems perform better long-term.

Date: Th, 08/13/2026, 3:20 AM | Message # 12

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How often should whole-house water filters be replaced?

I recently installed a whole-house water filtration system, but I'm not sure how often the filter cartridges should be replaced.

Is there a recommended replacement schedule, or does it depend on the amount of water the household uses? What are the signs that a filter is becoming clogged?

I've also noticed that the water pressure seems slightly lower than before. Could a dirty filter cartridge cause a noticeable drop in water pressure?

Should I replace the filter based on time, water usage, or pressure drop?

Date: Th, 08/13/2026, 3:20 AM | Message # 13

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How often should whole-house water filters be replaced?
The replacement interval for a whole-house filter depends on the type of filter, water quality, household water usage, and the manufacturer's recommendations.

A sediment filter may need to be replaced more frequently if the incoming water contains a lot of sand, rust, or other particles. Activated carbon filters have their own capacity and should generally be replaced according to the manufacturer's rated service life.

One of the clearest signs that a filter is becoming clogged is a gradual reduction in water pressure or flow, especially when the pressure was normal immediately after installing a new cartridge.
It's a good idea to install pressure gauges before and after the filtration system if you want to monitor the pressure drop across the filters. A significant increase in pressure difference indicates that the filter is becoming restricted.

Don't wait until the filter is completely blocked. A severely clogged cartridge can reduce flow throughout the house and make showers, faucets, and appliances perform poorly.

The best maintenance schedule is therefore a combination of the manufacturer's recommended replacement interval and the actual condition of the filter. If your water contains a lot of sediment, you may need to replace cartridges more often than a household with relatively clean municipal water.

When replacing a cartridge, also inspect the housing, O-ring and connections for damage or leaks. If pressure remains low after installing a new filter, the restriction may be elsewhere in the plumbing system.

Date: Fr, 08/14/2026, 8:38 AM | Message # 14

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Can RO wastewater be reused instead of going down the drain?

I'm considering installing an under-sink reverse osmosis system, but I'm concerned about the amount of wastewater it produces.

Instead of sending the reject water directly down the drain, can it be collected and reused for something like watering plants, cleaning, or flushing toilets?

Is RO wastewater safe for these uses, or does the concentrated water contain too many dissolved minerals and other contaminants?

Are there newer RO systems that produce less wastewater?

Date: Fr, 08/14/2026, 8:38 AM | Message # 15

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Can RO wastewater be reused instead of going down the drain?
Yes, RO reject water can sometimes be reused, but the best application depends on the quality of the incoming water and what contaminants are being concentrated by the RO membrane.

The wastewater contains the minerals and other dissolved substances that the membrane removes from the purified water, so it can have a higher concentration of dissolved solids than the original tap water.
For some households, this water can be collected and used for cleaning, flushing toilets, or other non-drinking purposes. Using it for plants requires more caution because the higher mineral or salt concentration may not be suitable for sensitive plants or for long-term irrigation.

Another option is choosing a high-efficiency RO system. Modern systems can use significantly less water than older designs, and some systems recover a greater percentage of the incoming water as purified water.

If water conservation is important, check the manufacturer's rated wastewater-to-purified-water ratio before buying the system. Don't assume that every RO system has the same efficiency.
For an under-sink installation, reusing reject water can be practical, but the collection system needs to be designed so that wastewater cannot flow back into the drinking-water supply.

A good setup for a home with hard water is still a combination of whole-house softening and point-of-use RO. The softener reduces hardness before the RO membrane, while the RO provides additional purification for drinking and cooking.

Date: Su, 08/16/2026, 3:11 AM | Message # 16

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Do I need a sediment filter before a whole-house carbon filter?

I’m planning a whole-house filtration system for municipal water. I mainly want to improve taste and odor, but I also occasionally see small amounts of sediment in the water.

Would it make sense to install a sediment filter before an activated carbon filter? Does the sediment filter help extend the life of the carbon cartridge, and how fine should the sediment filter be?

Date: Su, 08/16/2026, 3:11 AM | Message # 17

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Do I need a sediment filter before a whole-house carbon filter?
Yes, using a sediment pre-filter before an activated carbon filter is often a good configuration when the incoming water contains sand, rust or other visible particles.

The sediment filter captures larger particles before they reach the carbon media. This can help prevent the carbon filter from becoming clogged prematurely and maintain better flow through the system. The existing discussion in this thread already notes that sediment loading is one of the main reasons whole-house filters develop a pressure drop.

The correct micron rating depends on the water quality and the filtration system. A very fine sediment filter isn't automatically better: if it's unnecessarily restrictive, it can reduce household water pressure and require frequent replacement.

A practical approach is to start with a coarser sediment filter and use a finer stage only if testing or visible sediment indicates that it's necessary.

For example, a system might be arranged as:
Main water supply → sediment filter → activated carbon filter → house
If the water has significant hardness, remember that an activated carbon filter doesn't function as a water softener. Hardness is primarily caused by calcium and magnesium, so a water softener may be needed separately if scale is the main problem. The thread already distinguishes softeners from filtration and RO systems.

I'd also recommend installing pressure gauges before and after the filtration system. Monitoring the pressure difference makes it much easier to determine when a cartridge is becoming restricted rather than replacing it solely on a calendar schedule.

So, for municipal water with occasional sediment and a goal of improving taste and odor, sediment pre-filtration followed by activated carbon is a sensible starting point.

Date: Sa, 08/22/2026, 2:36 AM | Message # 18

Group: Guests

Can RO wastewater be used to refill a humidifier or steam appliance?

I have an under-sink reverse osmosis system and would like to reduce water waste. I understand that RO reject water contains a higher concentration of dissolved minerals than the original tap water.

Could this wastewater be collected and used in a humidifier, steam mop, or other household appliance instead of being sent down the drain? Would the concentrated minerals cause scale or damage?