Weddell Duo Shower Filter Review

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📊 Scoring Data

The Weddell Duo has a unique design that we were intrigued to test ourselves. 

We rank all the water filters we test based on a scoring system that comprises 6 key performance factors. We combined the Duo’s individual scores into an average overall performance score. See the table below for a breakdown of the data.

CriteriaResults
Health Related Contaminants84
Aesthetic Related Contaminants99
Performance CertificationCertified for 20% of reduction claims
Filtration Rate1.43 GPM
Component QualityExcellent
Component CertificationNot certified
SetupExcellent
Servicing RequirementsOutstanding
Costs$0.003/ gallon
Warranty LengthLifetime
ShippingFree shipping for lower 48 US states
Returns30 days, minus 10% restock fee

🚰 Contaminant Reduction

Score: 8.43

First and foremost, we wanted to know whether the Weddell Duo shower filter was capable of reducing the contaminants we were concerned about in our shower water. 

This involved conducting our own water quality testing and searching online to see if the Duo had obtained performance certifications from the NSF/ANSI, IAPMO, or the WQA for reducing select contaminants.

Our Performance Testing

Score: 8.48

We used a lab testing service called SimpleLab Tap Score to test our water before and after running it through the Weddell Duo. SimpleLab shipped us a kit to take our samples, which we returned to the lab for testing. We received our test results in two test reports. 

water testing with tap score

Note: Tap Score’s test reports are interactive, allowing you to compare your results to different health standards, including the EPA’s Maximum Contaminant Levels (MCLs) and Tap Score’s own Health Guideline Levels (HGLs). We assessed our water quality against the Tap Score HGLs, which prioritize human health and are stricter than the MCLs.

Shower filters project unfiltered water contaminants above HGL

Also included in our test kit was a chlorine testing strip, so we could get an accurate measurement of this chemical before it had the chance to dissipate. We also got a separate titration test because we wanted the most accurate, real-time understanding of our water hardness. 

Here’s what you should know about our testing conditions: 

  1. We only focused on contaminants that could be harmful in shower water. These were chlorine, water hardness, and DBPs. We evaluated the Duo based on its ability to address these contaminants since they were the only ones in our shower water that have known dermal and inhalation effects. 
  2. We used cold water in both tests. It’s obviously true that most of us shower in hot water, but we needed to be able to accurately test for disinfection byproducts (DBPs), which dissipate quickly, especially from hot water. 

Health-Related Contaminants

Score: 8.40

Starting with the health-related contaminants in our water, the Weddell Duo performed better than any other shower filter we tested.

The main contaminants we were concerned about were:

  • Disinfection byproducts, specifically:
    • 2.62 PPB of bromodichloromethane
    • 5.47 PPB of chloroform
    • 0.74 PPB of dibromochloromethane
    • 0.25 PPB of bromochloromethane
  • Around 2 PPM of chlorine

Bromodichloromethane, chloroform, and dibromochloromethane were all detected in concentrations exceeding the Tap Score HGL, making them potentially harmful to health. The concentrations of bromochloromethane didn’t exceed the Reporting Limit, so our testing lab was unable to evaluate its safety. 

Contaminant NameTypeUnitUnfilteredWeddellDifference
ArsenicMetalsPPM0.00023110.0002058-10.95%
BariumMetalsPPM0.031890.02505-21.45%
BicarbonateMineralsPPM148.14149.691.05%
BoronInorganicsPPM0.018970.00348-81.66%
BromochloromethaneDisinfection ByproductsPPB0.25-100.00%
BromodichloromethaneDisinfection ByproductsPPB2.62-100.00%
CalciumMineralsPPM34.4365633.57502-2.50%
CarbonateMineralsPPM1.680.95-43.45%
ChlorideInorganicsPPM19.88120.9435.34%
ChloroformDisinfection ByproductsPPB5.47-100.00%
CobaltMetalsPPM0.0000040.0000040.00%
CopperMetalsPPM0.07381-100.00%
DibromochloromethaneDisinfection ByproductsPPB0.74-100.00%
FluorideInorganicsPPM0.0040.0040.00%
HardnessPropertiesPPM127.82125.36-1.92%
Hardness (Ca,Mg)PropertiesPPM127.82125.36-1.92%
Hardness (Total)PropertiesPPM128.19125.59-2.03%
IronMetalsPPM0.000720.000720.00%
LeadMetalsPPM0.0002713-100.00%
LithiumMetalsPPM0.004210.00402-4.51%
MagnesiumMineralsPPM10.1584510.08299-0.74%
MolybdenumMetalsPPM0.00022440.000261716.62%
NickelMetalsPPM0.0004253-100.00%
Nitrate (as N)InorganicsPPM0.0060.0060.00%
pHPropertiespH8.398.14-2.98%
PhosphorusInorganicsPPM0.005870.154022523.85%
PotassiumMineralsPPM2.014572.030550.79%
SodiumMineralsPPM12.243911.81576-3.50%
StrontiumMetalsPPM0.187370.18314-2.26%
SulfateInorganicsPPM19.88718.575-6.60%
Total Dissolved SolidsPropertiesPPM206.7212.72.90%
Total THMsDisinfection ByproductsPPB8.83-100.00%
UraniumMetalsPPM0.00053250.0002069-61.15%
VanadiumMetalsPPM0.000166-100.00%
ZincMetalsPPM0.009190.00044-95.21%

💡 Why are we concerned about the health effects of disinfection byproducts? We found scientific studies, including this 2020 study, that highlight the possible dangers of DBPs, particularly THMs, in shower water. Health effects include an increased risk of several “cancer and non-cancer risks” when inhaled. 

Weddell says that the Duo filter can reduce chlorine, microplastics, PFAS, lead particles, and unpleasant odors—and the good news is that it lived up to its marketing claims in our testing.

In fact, of all the shower filters we tested, the Weddell Duo was the only filter that removed all disinfection byproducts (the other filters we tested didn’t actually address DBPs at all). 

So what makes the Duo capable of removing these contaminants? We think it’s most likely because it’s the only shower filter we used that has a solid carbon block filter. These filters are more compact than granular carbon filters, enhancing their ability to adsorb contaminants, including trickier-to-remove contaminants like DBPs. 

Weddell Duo activated carbon block filter

No surprises, the Duo filter also effectively removed 100% chlorine, so it’s a great all-rounder for targeting chlorine and its byproducts. 

Water Hardness

There were two methods that we used to measure the hardness of our shower water: with our Tap Score lab test and with a more precise on-site titration test. 

  • In our initial Tap Score test, our unfiltered water had a total hardness reading of 128.19 PPM, or 7.49 GPG, putting it in the “hard” category.
  • Our first on-site titration test detected a water hardness of 8 GPG. 

Does hard water pose a health risk? No—at least not in the same way as disinfection byproducts, which is why we’re discussing it in a separate category. Hard water doesn’t increase the risk of serious health effects, but studies have found that it damages the skin barrier, leading to the exacerbation of skin conditions like eczema. 

Weddell doesn’t claim that the filter reduces water hardness, so we had no reason to believe that it would affect our hardness at all.

It’s important to note that this isn’t a setback of this specific filter—most shower filters (despite some brands’ misleading claims) are unable to reduce water hardness because they don’t contain ion exchange resin.

If you specifically want to address water hardness, you need a water softener or a shower filter that does use a cation exchange resin, like the Shower Stick.

Contaminant Reduction Claims

There are several contaminants that Weddell claims to reduce that we want to quickly talk about here. 

Aside from chlorine and its associated odors, the Duo shower filter is marketed as a solution to reduce microplastics, PFAS, and lead particles.

In our testing, the Duo eliminated 100% lead, bringing the initial concentration of 0.0002713 down to 0. 

Our water didn’t contain PFAS or microplastics, so we couldn’t test the filter’s ability to remove these contaminants. 

Performance Certifications

Score: 8.00

To support their contaminant reduction claims with actual evidence, shower filter manufacturers can apply to get their products certified by the NSF, the WQA, or IAPMO. The most commonly-sought certification for a shower filter is NSF 177, for the reduction of chlorine. 

Brands can still make performance claims without getting their filters certified, but it’s reassuring to see official proof of contaminant reduction from a reputable testing organization. 

The Weddell Duo has an NSF certification to Standard 177 for its ability to reduce chlorine. It’s only certified for the reduction of 1 of the 5 contaminants that Weddell claims it can reduce, which is a good start, but prevented it from getting the highest score in this category.

🚦Filtration Rate

Score: 10.00

Weddell claims the filter’s maximum flow rate is 2.80 GPM, noting that the actual flow rate you’ll get depends on your showerhead and not the filter itself. That essentially means that the maximum 2.80 GPM flow rate is only achievable if you have a fast-flow showerhead and great water pressure to start with. 

We conducted our own tests to see how our own flow rate was affected by the Weddell Duo shower filter. This included timing how long it took to filter 2 cups of water, then repeating the test twice more and taking an average time from all three. 

We measured a flow rate of 1.43 GPM from the Duo filters, with an average time of 5.23 seconds to fill 2 cups with filtered water.

This is slower than all the other shower filters we tested, which probably has something to do with the fact that there are two separate cartridges for the water to flow through, while all the other filters only had one.

That said, we didn’t notice a drop in our water pressure after installing the unit, so we believe Weddell is correct about the flow rate being linked to your existing shower head and original water pressure. 

📐 Design

Score: 7.80

The Duo is Weddell’s only shower filter offering, and it has an inline design, meaning that it sits directly upstream of your existing showerhead.

There are two filter cartridges that are contained inside a cylindrical unit that sits horizontally on your shower arm. This design meant that our showerhead didn’t get extended downwards as far as some of the other single-cartridge filters we tested, with the filter sitting centrally in the unit.

Weddell Duo minimal shower head length extension

You can buy the unit in three finishes: 

  1. Black
  2. White
  3. Pink

In terms of how it looks, it is quite bulky due to its horizontal design, so it’s not going to completely blend in with your showerhead, but its design is quite attractive and doesn’t stand out too much.

Component Quality

Score: 9.00

The Weddell Duo has a solid, sturdy feel, and was one of the best filters we tested in terms of design quality. Many shower filters feel plasticky and flimsy, but the Duo feels like it’s built to last. 

Something to note, however, is that the unit is made from plastics, so even though Weddell claims the filter offers microplastics reduction, you will still be increasing your exposure to plastic with this shower. 

Filter Materials

The Weddell Duo combines two separate filter cartridges: 

  1. A sediment filter 
  2. A proprietary activated carbon filter, which contains “multi-stage condensed layers”
Weddell Duo sediment and carbon block filter cartridges

We don’t often see a sediment filter used in a shower filter, but it’s a good way for Weddell to enhance the contaminant reduction ability of the carbon filter by removing contaminants that could clog up the media. 

Materials Safety Certification

Score: 6.00

Similarly to performance certifications, materials safety certifications can be applied for by manufacturers to provide third-party reassurance of their filter’s design. They’re optional, demonstrating that the product has been tested under professional conditions and deemed compliant with the NSF’s materials safety standards. 

Unfortunately, Weddell hasn’t obtained a materials safety certification for the Duo, so it got the poorest score from us in this category.

⚙️ Setup

Score: 9.00

The Weddell Duo was easy to install, and the entire setup process took less than five minutes. 

We just unscrewed our shower head, applied plumber’s tape to the Duo, then screwed the filter onto our existing shower arm and re-attached our showerhead.

We also flushed the filter (a process that removes any loose carbon) by running water from our shower for three minutes. 

Setup is tool-free, as with most shower filters, so you won’t need to get help from an expert or make permanent changes to your plumbing.

🔧 Maintenance

Score: 9.75

We also gave the Duo a high score in the maintenance category, thanks to its easy and affordable servicing. 

Servicing Requirements

9.50

Weddel’s dual-filter design was ideal from a maintenance perspective, meaning that we could simply unscrew one of the side filter housings rather than remove our entire shower head to replace a filter. 

Weddell recommends replacing the filters every 5-6 months or when you notice that your water pressure decreases significantly.  We liked being able to check the appearance of the filters through the clear housings to see when they looked visibly dirty (a sign that they needed replacing). 

Costs

Score: 10.00

The Duo is a mid-range filter in terms of its upfront cost, but we were keen to know how its ongoing maintenance spend compared to similar systems. 

We calculated the filter’s ongoing cost at just $0.003/ gallon, based on Weddell’s claimed filter lifespan and the cost of replacement filters.

That’s pretty impressive given that the Duo is the only shower filter we tested that has two separate cartridges, and it was still one of the cheapest to maintain.

ProductUpfront CostReplacement Filter Cost/ gal.
Shower Stick$375.00$0.002
Jolie$165.00$0.012
Canopy$150.00$0.012
Aquasana$119.99$0.006
Weddell$89.99$0.003
Hello Klean$87.00$0.015
Berkey$60.00$0.003
AquaBliss$59.95$0.002
Sprite$35.00$0.002

Read Also: Jolie shower filter review

🏢 Company

Score: 8.80

Our final point of assessment was Company. We looked at Weddell’s warranty, shipping, and returns offerings to determine its reputability and reliability as a manufacturer. 

While Weddell did better than most other shower filter manufacturers with its warranty and shipping offerings, its poor returns policy reduced its score in this category. 

Warranty

Score: 10.00

Weddell is the only shower filter brand we’ve come across so far that offers a lifetime warranty for its products. We did some digging into the warranty terms, and we couldn’t find a specific warranty period (i.e. a “lifetime” warranty is usually only for the unit’s expected lifespan, which could be anything from 1 to 10+ years). 

The warranty entitles you to a refund or replacement if the filter is “discovered to have manufacturing defects or faulty materials”. For your warranty claim to be eligible, Weddell says that proof of purchase “may be required”.

Learn more about Weddell’s warranty here

Shipping 

Score: 9.50

Weddell also got a great score for its shipping offering, being one of the few shower filter manufacturers we reviewed that offers free shipping to all contiguous United States. That means your initial purchase of the filtration system and all replacement filter purchases get shipped for free, with no minimum spend. 

Here’s the link to Weddell’s shipping policy. 

Returns

Score: 6.5

Returns is something that seriously let Weddell down in the Company category. 

The company does at least offer some form of money-back guarantee: a 30-day returns policy. But there’s a 10% restock fee, so you can’t try the system with the security of knowing that you’ll get a full refund if you don’t like it within the trial period. The fee even appears to apply if you receive a defective item, which isn’t very fair. You also can’t return used or opened replacement cartridges.

View Weddell’s returns and exchanges policy here.

💰 Value For Money

So, is the Weddell Duo worth its upfront and ongoing cost? Based on our experience, yes. 

It was the only shower filter that successfully targeted disinfection byproducts in our testing, and not only that, it eliminated them entirely. That’s its biggest selling point given the known dangers of DBP exposure in water vapor. 

The fact that it also reduces PFAS and microplastics, which (according to emerging evidence) may potentially be dangerous in shower water is also a bonus, although we couldn’t validate these claims with our own limited testing. 

The Duo costs less than $100 and is one of the more affordable shower filters we tested, with a super low maintenance cost despite having twice the number of filter cartridges as the rest. 

Are there any potential dealbreakers here? Perhaps if hardness is one of the main water quality issues that you want to address, in which case, you will need to go for a specialized filter or even better a point of entry water softener. 

Overall, though, we’d recommend the Weddell Duo over all the other shower filters we tested. It got the highest overall performance score and did the best job at removing the contaminants we were concerned about.

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  • brian headshot
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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