Overview

We see many of our fellow RVers using in-line water filters to improve the quality of the water in their RV. Most of us use these filters to get rid of sediment, improve the taste and odor of the water, and hopefully reduce other minerals in the water that might damage our plumbing.

An in-line water filter is a filter that you connect in between the water spigot provided by the RV park and your RV. Basically, you screw the water filter into the water spigot on one side, and your fresh-water hose on the other side. 

But which filters are best at actually filtering the water? Does the $50 filter deliver better quality than the $12 filter?

Our goal was to evaluate the performance of five of the most common low-cost water filters we see used on recreational vehicles. 

How We Tested

We tested water at seven different RV parks using consumer water test strips in order to find a location with poor water quality. Once we found a location with poor quality, we then tested the water using a precise protocol that included running water through each filter for the manufacturer’s recommended minimum time before taking a sample. We tested the water using both consumer test strips from Baldwin Meadows, Hach, JNW and Hone Forest (TDS Meter) and also sent samples of water from each filter for evaluation by Tap Score, a commercial testing laboratory.

We compared the results for each RV water filter from the Tap Score lab report and our consumer test strips. For our recommendation here, we rely exclusively on the results from Tap Score.

Recommendation

Overall Best Choice
Camco TastePURE RV/Marine Water Filter (about $17) Buy Now on Amazon

This filter performed better than lower-priced filters, and equal to or better than higher-cost filters. This filter reduced total dissolved solids, Aluminum, LSI, Chlorine, Copper, Magnesium, Nitrate, Phosphorous, Potassium, and Sodium in our professional lab tests. It includes an activated carbon filter, the housing is secure, and it comes with a convenient flexible hose protector. For the price and convenience, this is the best filter you can purchase. This product comes in two sizes, the regular and XL sizes. We tested the regular size. Notably, the higher-cost version of this product, the Camco Evo Premium, did not perform nearly as well as the lower-cost unit.

Products We Tested

Culligan	AquaCrest	Camco	Camco	EcoPure
RV-8001 Water Filter	RV Inline Water Filter	TastePURE RV/Marine Water Filter	Evo Premium RV & Marine Filter	EPWO4 Whole House Filter
$22	$9 ($18 for 2)	$17	$34	$54
Buy on Amazon	Buy on Amazon	Buy on Amazon	Buy on Amazon	Buy Case / Filter

Key Findings

The lowest-price filter, the AquaCrest RV Inline Water Filter, which appears to be exactly the same filter sold by Amazon as its Amazon Basics filter, performed reasonably well. This product includes two filters in the box for about the same as a single Camco TastePURE filter but when we purchased it, did not include the useful flexible hose protector, which you will most likely need to successfully connect the filter to your RV. This Aqua Crest filter also performed less well at reducing calcium, copper, and also increased the amount of zinc in the water, but still within safe levels. (Zinc is sometimes used in the manufacturing of activated carbon, and may have been present initially in the filter.) 

The Culligan RV-8001 Water Filter performed well and beat the Camco TastePURE on a few parameters: Conductivity, Langelier Saturation Index (LSI) and calcium. However, it underperformed on other key parameters, and of great concern, appeared to increased the level of nitrites (See the section, Filters Can Make Your Water Worse, below). Overall, we felt that this filter was not worth the cost premium. Although we did not evaluate the impact of different filter housings, the Culligan housing felt lower-quality, almost like heavy cardboard, and was damp to the touch in the morning after being left outside overnight.

The most expensive filter, the EcoPure EPW04 Universal Large Capacity Whole Eater Filter with an impressive 1-micron filter, did not perform better than the other filters, and also does not include any carbon filtering with the filter we tested, although other, more expensive carbon filters are available. Also, recognizing that the EcoPure was designed really for a whole-house system, it would require additional equipment and effort to connect it to your RV, whereas the other filters are designed for easy connections to your RV. Of all the filters we tested, however, the housing of this unit was the most sturdy, and likely to last years.

Poor Quality Filters Can Make Your Water Worse

Two of the filters we tested appeared to negatively impact the quality of the water. The Culligan RV-8001 Water Filter and the Camco Evo Premium RV & Marine Filter both appeared to increased the level of harmful nitrates in the water, while the other filters reduced the nitrites in the water source. Straight out of the water spigot, our commercial testing center, Tap Score measured nitrites in the water source at 4.5 parts per million (ppm). The Culligan RV-8001 increased nitrates in the water to 5.6 ppm and the Camco Evo Premium increased nitrates in the water to 9.5 ppm. 

Nitrogen is an essential nutrient for plants and is commonly used for agricultural and lawn care purposes. Nitrates (and nitrites) typically enter your drinking water from runoff due to animal waste, fertilizer, natural deposits, septic tank leakage, and sewage. Nitrites rapidly transform into nitrates. Methemoglobinemia or “blue baby” syndrome is a severe risk when nitrate levels exceed 10 PPM and an infant or a pregnant woman is exposed to such water.

We talked with the Tap Score lab about these troubling findings. Tap Score confirmed their findings. Impressively, Tap Score tests each water sample three times for each parameter (including nitrates), and then takes the average of all readings, unless one is unusually high or low, in which case they test the sample again. The lab suggested that the commercial process of creating lower-quality forms of activated carbon can leave residual nitrate in the carbon, and the high level of nitrites we measured are likely the result of the manufacturing process to create activated carbon, and would most likely be washed away and reduced gradually as water was run through the filter over a period of days.

Other Findings

All filters we tested decreased the Langelier Saturation Index (LSI) by 50% or more. The best performing filter was the Culligan filter for this test. LSI is an indicator of the degree of saturation of calcium carbonate in water. If the LSI is positive, then the water is over-saturated with calcium carbonate and will tend to deposit calcium carbonate forming scales in the distribution system. If the Langelier Index is close to zero, then the water is just saturated with calcium carbonate and will neither be strongly corrosive or scale forming. The spigot water we measured (without filters) was 0.41 LSI, and the Culligan filter reduced the LSI to 0.14 and the Camco TastePure reduced the LSI to 0.19.

Finally, Uranium was detected at a small, but measurable level of 0.022 PPM parts per million (PPM) in the water source we tested. It’s unlikely that you will find uranium in your water, but the level of uranium in the water was not impacted by any of the filters. Uranium is commonly detected in groundwater and soil. It enters drinking water from natural sediments and from irrigation and runoff. The chemical effects of uranium in drinking water are usually a greater concern than the possible effects of its radioactivity. It has been associated with a slightly increased risk of cancer as well as kidney and liver damage.

Limitations of Our Testing

Iron and Lead: In addition to filtering the elements we were able to measure in this test, filtering of lead and iron is one area that in-line filters could possibly make a valuable difference. However, we were not able to find measurable levels of iron or lead in the locations we scouted to perform this test.

Filter Choice: We selected these filters based on our ad-hoc evaluation of the most common filters we saw over a one-month period traveling primarily in California, Nevada, Arizona and which filters Amazon.com reports are best-sellers and easily available for shipping. The EcoPure EPWO4 Whole House Filter was used by a colleague who is a rigged this system into his RV and highly recommended it as a more environmentally sustainable unit (because the filter can be replaced while the filter housing could last many years). We also limited ourselves to just five filters, because of the cost of commercial testing.

Next Steps

If this test proves valuable to the community, and we seek to perform it again, we would likely do so with a wider set of filters, and also identify a water source with measurable levels of iron and lead.

If you are aware of what you think is a poor water source that also has high iron and lead levels or you recommend a widely-available and popular filter that we should test, please let us know in the comments following this review.

Special thanks to Jeff M., a water quality engineer and friend who provided extensive advice as we developed our testing protocol, and Johnny P. from Tap Score, our commercial testing lab, who helped us understand variations in our water quality findings. Any possible errors, misinterpretations or omissions are solely our fault, and not those of these advisors.

Thanks for reading. And remember: Travel Smart. Live Better.