Oz filter warehouse blog article
What we'll cover in this article.
In this guide, we compare CTO and PB1 side by side, explain the key differences and help you work out which option may be the better fit for your Crystal Series whole house water filtration system.
The quick comparison
The main differences between CTO and PB1 at a glance.
When CTO may be more suitable
Find out when CTO may be a good fit for households looking for effective carbon filtration with lower relative flow resistance.
When PB1 may be more suitable
Learn when PB1 may suit households wanting finer filtration and support for reducing additional contaminants.
5-micron versus 0.5-micron
Understand what the micron ratings mean and how filtration fineness can affect performance and flow.
What does each filter help reduce?
Compare what each filter is designed to reduce.
FAQs
Get simple answers to common questions about CTO, PB1 and whole house carbon filtration.
CTO vs PB1
Which carbon filter is right for your whole house water system?
Choosing between a CTO and PB1 carbon filter can feel a little confusing when both are designed to improve the quality of your household water. While they share some similarities, there are also important differences in how they filter water and the types of contaminants they are designed to reduce.
The right option will depend on what matters most in your home, including your water quality concerns, the level of filtration you are looking for and your household's water flow requirements.
In this guide, we compare CTO and PB1 side by side, explain the key differences and help you work out which option may be the better fit for your Crystal Series whole house water filtration system.
The quick comparison
CTO and PB1 are both carbon filtration options available for the Crystal Series, but they suit slightly different household priorities. The main differences come down to filtration fineness, supported contaminant reduction and the level of resistance they create as water moves through the filter.
| Feature | CTO | PB1 |
|---|---|---|
| Nominal filtration | 5 micron | 0.5 micron |
| Chlorine reduction | Yes | Yes |
| Chloramine reduction | Yes | Yes |
| PFAS reduction | Yes | Yes |
| Taste and odour improvement | Yes | Yes |
| Lead reduction | Not listed as a key supported reduction | Yes |
| VOC reduction | Not listed as a key supported reduction | Yes |
| Selected cyst reduction | Not listed as a key supported reduction | Yes, through mechanical filtration |
| Relative flow resistance | Lower | Higher |
That does not necessarily make PB1 the better choice for every home. The best option depends on what you want to reduce from your water and how much importance you place on maintaining household flow.
When CTO may be suitable
CTO may be a good fit if you are looking for effective whole house carbon filtration while keeping household water flow in mind.
What does CTO help reduce?
With 5-micron nominal filtration, CTO is designed to reduce chlorine, chloramine and PFAS, while also helping improve unwanted tastes and odours in your water. This makes it a practical option for households whose main concerns are the common chemicals and characteristics associated with treated mains water.
What about household water flow?
CTO has lower relative flow resistance than PB1. This may be useful in homes with higher water demand or where several taps, showers or appliances are often being used at the same time.
Who might CTO suit best?
CTO can offer a good balance between contaminant reduction and household flow. If your priorities are improving the overall quality, taste and smell of your mains water without requiring the finer filtration or additional supported contaminant reduction of PB1, CTO may be all you need.
When PB1 may be suitable
PB1 may be a good fit if you are looking for finer filtration and want to target a broader range of contaminants throughout your home.
What does PB1 help reduce?
PB1 is designed to reduce chlorine, chloramine and PFAS, along with lead and VOCs. It also helps improve unwanted tastes and odours in household water.
What does the 0.5-micron rating mean?
PB1 has a nominal filtration rating of 0.5 micron, making it considerably finer than the 5-micron CTO option. This finer mechanical filtration also supports the reduction of selected cysts. It is important to note that this does not sterilise or disinfect the water and should not be treated as a substitute for disinfection where microbiological protection is required.
Who might PB1 suit best?
PB1 may suit households that want the additional contaminant reduction it offers, particularly where lead, VOCs or finer mechanical filtration are priorities. It can provide a broader level of filtration than CTO, but that additional filtration also needs to be considered alongside household flow requirements, which we will look at further below.
5-micron versus 0.5-micron nominal filtration
The micron rating tells you how fine the filtration is. A smaller micron number means the filter is designed to capture smaller particles as water passes through it.
CTO has a nominal rating of 5 micron, while PB1 has a much finer nominal rating of 0.5 micron. In simple terms, PB1 filters at a finer level than CTO.
That finer filtration can be useful if you are specifically looking for the additional contaminant reduction supported by PB1. However, a smaller micron rating does not automatically mean it is the better option for every household.
Finer filtration can also create more resistance as water moves through the cartridge. This is why it is important to look at micron rating alongside your household's water demand, rather than choosing based on the number alone.
The best option is the one that gives you the level of filtration you need while still working well with the flow requirements of your home.
Supported contaminant-reduction differences
There is some overlap between CTO and PB1, but the key difference is the range of contaminants each filter is designed to reduce.
Both options are designed to reduce chlorine, chloramine and PFAS, while also helping improve unwanted tastes and odours in your water. For many households, these are some of the main reasons for choosing a whole house carbon filtration system in the first place.
PB1 goes a step further by also supporting reduction of lead, VOCs and selected cysts through mechanical filtration. This can make it a better fit if those additional contaminants are a particular concern in your home.
The best choice depends on which contaminants matter most to your household. If chlorine, chloramine, PFAS, taste and odour are your main priorities, CTO may provide the level of filtration you are looking for. If you also want support for reducing lead, VOCs and selected cysts, PB1 may be the more suitable option.
Flow and pressure considerations
Flow and pressure are worth considering when choosing between CTO and PB1, particularly in homes with higher water demand.
Because PB1 filters more finely, it has a higher stated pressure drop than CTO. In practical terms, that means it creates more resistance as water moves through the cartridge. CTO has lower relative flow resistance, which may suit households where maintaining stronger flow across multiple taps, showers or appliances is a priority.
That does not mean PB1 will automatically create poor water pressure. The overall result depends on factors such as the incoming water pressure, household demand and the way the system is configured.
This is why filtration performance and household flow should be considered together. If you want finer filtration and the additional contaminant reduction offered by PB1, that may be the right trade-off for your home. If lower flow resistance is more important, CTO may be the better fit.
So, should you choose CTO or PB1?
The choice between CTO and PB1 comes down to what you want your whole house filtration system to prioritise.
If your main concerns are reducing chlorine, chloramine and PFAS, improving taste and odour and keeping relative flow resistance lower, CTO may be the better fit.
If you want finer 0.5-micron nominal filtration along with supported reduction of lead, VOCs and selected cysts, PB1 may be more suitable.
There is no one-size-fits-all answer. The best option is the one that matches your household's water quality concerns and flow requirements.
If you are unsure which carbon option to choose for your Crystal Series system, get in touch with our team and we can help you balance filtration performance with the water demand of your home.
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FAQs
If you're new to water filtration or considering a system for your home, the answers below cover some common questions we hear.
Will I notice a difference in the taste and smell of my water?
Both CTO and PB1 are designed to help improve unwanted tastes and odours in household water, so either option can be a good choice if this is one of your main concerns.
Does CTO still reduce PFAS?
Yes. CTO is designed to reduce PFAS alongside chlorine and chloramine, while also helping improve unwanted tastes and odours in household water.
Can a whole house water filter reduce chlorine?
Yes. A whole house water filter with activated carbon can help reduce chlorine, along with the unwanted taste and odour it may cause. The system treats the water before it moves through the connected household plumbing.
What if I am still not sure which one to choose?
That is completely normal. CTO and PB1 are both strong options, just with slightly different strengths. If you are unsure, our team can help you choose the option that best suits your household, water concerns and flow requirements.
