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The Best RV Holding Tank Sensors (Most Accurate)

Written by Stephen Ryan / Fact checked by William Turner

best rv holding tank sensors

First-time RVers do not realize it, but getting the best RV holding tank sensors can make a world of difference in their outdoor adventures.

These devices empower RV families to know if their fresh water supply is running low, requiring tapping into an RV park water utility. Knowing when to dump the waste from the gray and black holding tanks is also easier with a tank monitoring system.

Choosing a sensor for motorhome holding tanks can be daunting to the uninitiated and people with RVs without built-in tank monitoring systems. Complicating the shopping woes is the absence of clear differentiation among products.

RVers can rest assured because our extensive search points to three crucial considerations when buying a motorhome holding tank sensor.

  • Material: RV tank sensor materials differ across types. For example, internal probes require rust- and corrosion-proof sensors because they are in constant contact with the tank’s content.

Excellent material for such products is stainless steel. On the other hand, external sensors need excellent conductivity because of their position outside the tank.

  • Installation Ease: Like material composition, a holding tank sensor’s installation ease depends on its type. External probes are the most straightforward to set up because they do not require drilling through the tank’s sides.

Meanwhile, internal sensors need precisely-cut holes in the tank for probe insertion.

  • Cost Effectiveness: An RV holding tank monitoring system has three essential components –probes, wires, and an indicator panel. RVers can choose to buy these parts separately to save money.

Unfortunately, there are no guarantees each element will last as long as the others. In such cases, a complete kit is more cost-effective because of compatibility among components.

These are not the only considerations buyers of RV holding tank sensors must know. We also identified a few others, which we will present and highlight in the buying guide and product review sections.

Top 1

RecPro Water Level


Dimensions ‎4.69 x 2.17 x 0.83 inches
Weight 1.76 ounces

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Top 2

Valterra T21301VP


Dimensions ‎7.5 x 3.75 x 1.5 inches
Weight ‎0.704 ounces

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Top 3

RecPro RV Tank Sensor


Dimensions 7.4 x 4.84 x 1.97 inches
Weight 3.87 ounces

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5 Best Holding Tank Sensor for RV

1. RecPro Water Level Screw-in Sensors

I have never doubted RecPro products. And I am sure many RVers have the same view. Hence, it comes as no surprise that one of the best motorhome holding tank sensors comes from this brand. This model is a trustworthy probe, effectively replacing third-party sensors.

RecPro tank sensors are some of the world’s best, if not the industry leader. A friend of mine experienced years of a malfunctioning RV holding tank monitoring system. Frequent sensor cleaning and parts replacement did nothing to solve the problem. Everything started working like when he swapped to this product.

That is the confidence this brand brings to many seasoned RVers. I never questioned this company’s product quality, performance, and reliability.

I trust this item’s rust-resistant properties. Although uncertain about the materials, I remain confident about its overall build quality. It has a rubber ring that plugs into the insertion point well. It is excellent news for users wary of drips from their holding tanks.

This RV holding tank sensor works best as a replacement probe, whether on freshwater, gray, or black water tanks. I can imagine owners of older vehicles without monitoring systems setting this product without issues. Of course, they must drill holes in the correct locations to make this sensor work.

One thing I observed about this product is its shorter length than conventional holding tank sensors. It measures about an inch long, including the sensor post. That makes its probe about 5/8 of an inch long. I know some RVers prefer longer sensors.

  • Rust-resistant properties for long-lasting and smooth function
  • Rubber ring to prevent leaks and drips
  • Easy to install with some drilling
  • Replacement for third-party parts on different tanks (black, gray, freshwater)
  • Reliable brand with good reviews
  • Some RVers might prefer a longer sensor probe
Still, I trust the brand’s excellent reputation for making dependable products. This model might be more compact than usual, but its performance and construction are unquestionable. It makes for a valuable investment for RV owners.

2. Valterra T21301VP Horst Miracle Probe

Although I love the RecPro, others might not agree with me, as they prefer an extended sensor probe for their RV holding tanks.

That is why I recommend the Valterra T21301VP Horst Miracle Probe. These black tank sensors are as reliable as the RecPro. Established in 1981, Valterra strives to produce high-quality after-sales RV products to make people’s adventures worthwhile.

This black holding tank sensor is one of the most reassuring offerings from the company, giving motorhome owners peace of mind when monitoring their black tank levels.

This product’s design makes it a dependable replacement for OEM sensors. People can plug it into an existing 3/8-inch hole in their black water tanks and never worry about getting erroneous readings again. Because it has a universal design, I do not see any complications if people install this sensor into their RV tanks.

My favorite thing about this item is its “hood” or “roof,” preventing undissolved, RV-unsafe toilet paper from interfering with the probe. One issue with “bare” tank sensors is that organic matter can adhere to the surface. I am glad I do not have to worry about such concerns with this product.

Unfortunately, the rubber ring does not expand as well as RecPro, increasing the likelihood of leaks. Most RVers solve this issue by applying a sealant on the O-ring before tightening the bolt.

  • Specifically for RV black water tanks
  • Fits ⅜-inch holes and replaces OEM parts
  • A universal design for easy installation
  • Integrated sensor “roof” for accuracy
  • Reliable brand for camper products
  • Rubber washers do not expand much
Camper owners with faulty black water tank sensors can effectively replace them with this product. The probes are long, and they work well in notifying RVers about their holding tank’s capacity status.

3. RecPro RV Tank Sensor Monitor Panel M21

RecPro returns with the Micro Monitor RV Tank Sensor Monitor Panel, a decent device that effectively replaces conventional KIB panels. Although this gadget is for camper holding tanks, its functionality extends beyond motorhome components.

To begin with, installation is never a problem as long as RVers follow the instructions. The best part is this gadget does not only connect to freshwater, black, and gray holding tanks. It can also alert motorhome owners about their RV battery levels. After all, the device connects to the vehicle’s 12-volt system.

The implications are immense. I can check the capacity of my power bank and motorhome holding tanks using only this device. It can link to four probes in each tank and display their status (full, 2/3, 1/3, and empty), giving users a comprehensive idea about their system’s operational state.

Surprisingly, this sensor panel controls the RV water pump and water heater. It does not matter if we have a gas-powered or electric water heater because they can wire this device to manage both types.

Need I say more about this brand’s credibility? I am one of the thousands of RVers more than satisfied with this third-party parts and accessories provider.

As impressive as this tank level indicator is, it is not as “smart” as other brands with Bluetooth functionality. For example, I love the Garnet 709-BTP3 SeeLevel II Tank Monitoring System because of its wireless capabilities, enabling me to track my holding tank’s status from my phone.

  • Trustworthy KIB indicator panel replacement
  • Can monitor RV battery level
  • Integrated controls for water pump and heaters
  • Effortless installation, linkable to black, gray, and freshwater tanks
  • Dependable brand for RV parts
  • No Bluetooth feature
Regardless, this RV tank sensor monitor panel is still leaps and bounds ahead of other brands. RecPro’s reputation is reassuring, allowing families to feel more confident about their purchases.

4. Briidea Micro Monitor System RV Tank Sensor

The Briidea RV Tank Sensor Monitor Panel stakes its claim as an excellent alternative to the RecPro M21 Micro Monitor. Both devices look uncannily similar, including their functionality. The major difference is their price, with this RV water tank level indicator panel gaining the upper hand among budget-conscious RV owners.

It might be less expensive than RecPro, but this sensor monitor panel never reneges on its promise. I have seen RVers rating this product five stars, and I can only assume it is because of its combination of affordability and performance.

Like the RecPro, this tank sensor monitor panel has a small footprint, allowing RVers to install it anywhere in their motorhomes. Space will never be a concern.

I also love this product’s generous after-sales policy, including a one-year warranty and a no-questions-asked refund rule. Unfortunately, I am unsure if the money-return period is as long as its guarantee support. Still, I commend the company for offering a better-than-most agreement.

At the moment, I do not have any complaints about this item. The markings are easy to read, and there’s a wiring diagram to help users with the installation. Plus, all parts necessary for setup already come with the monitor.

  • Dependable Micro Monitor replacement
  • More affordable than other tank sensor monitor panels
  • Space-saving design
  • No-questions-asked refund policy with 12-month guarantee
  • Markings are easy to read
  • Comes with wiring diagram and installation parts
  • No complaints thus far
RVers who do not mind a Chinese product will find this motorhome tank sensor monitor an excellent buy. Not only is it affordable, but it performs like the leading brand, too. It proves to everyone (including myself) that Chinese products deserve a place in the competitive RV parts marketplace.

5. Full Spectrum Parts RV Black Water Level Probes

These Full Spectrum probes are cost-effective alternatives for most sensors. They can be a reliable replacement for a motorhome owner’s existing RV tank monitoring system without the prohibitive price tag of leading brands.

In detail, buyers can get four sensors per pack, making this item more cost-effective than the Valterra.

These items are perfect for keeping tabs on black water tank levels. Travelers will know when to drive to an RV park with a dumping facility and empty their sewage container. Scheduling the next black water tank cleaning is also a breeze with these sensors in place.

Camper owners can replace defective or aging probes and never worry about getting erroneous readings again. Like the Valterra, this design has a shroud covering its low-voltage electrode. The design minimizes, if not eliminates, false activations (or inactivation) and ensures more reliable tank management.

Installation is a breeze, especially for tanks with existing sensors. RVers only need to remove the old ones and pop these probes through the holes. Of course, users who wish to set up these sensors in a probe-less tank must drill openings in the right places. Still, setups should not take more than an hour.

Unfortunately, brand-conscious buyers might not like these black water level probes. The scarcity of information about this company might be a red flag for some. Still, I cannot question its performance or its quality construction.

  • Recommended for black water tanks
  • Integrated shroud for better accuracy
  • Can replace old tank sensors and monitors
  • Slightly more affordable than leading black water tank probes (4 items/pack)
  • Easy installation, should take no more than an hour
  • A not-so-popular brand
It might not be as popular as the RecPro or Valterra, but this RV holding tank sensor is a sound option for replacing one’s aging tank probes.

What to Look for When Buying RV Holding Tank Sensors


Holding tank sensors for motorhomes are indispensable devices for a more efficient and hassle-free RVing experience. These gadgets have a simple design, yet their functionality can make RV freshwater supply and waste management more effective.

The question now is what should we look for when buying these products for travel trailers, fifth wheels, campers, caravans, and other vehicles?

  • Material

Like other products, an RV holding tank sensor’s material is crucial. However, it is worth noting that material characteristics vary across sensor types. Buyers must recognize that camper tank sensors come in two kinds – internal and external.

As the name implies, an internal RV tank level sensor has the probe inside the holding tank.

The material for these devices must have excellent resistance against corrosion and rust because they are in constant contact with liquid (freshwater, wash or bath water, and sewage). Most internal tank sensors feature stainless steel, while some brands use proprietary rust-proof technologies.

On the other hand, an external holding tank level sensor requires a different composition.

These products must have superior conductivity because their position on the tank’s outside surface places them away from the liquid tank content. Poor conductivity can prevent the power loop from completing, leading to erroneous readings on the indicator panel.

Moreover, external sensors must have excellent adhesive properties to guarantee they do not fall from the tank’s sides. Sadly, some options have mediocre self-sticking components, peeling from the surface when one drives on bumpy roads.

Buyers must also check the quality of wires and sensor indicator panels if they choose a complete kit. Sadly, online shopping robs RVers of the chance to examine and test the products before buying.

However, they can read customer reviews and pay attention to mentions of unreliable lights, broken switches, fragile cables, and similar concerns.

  • Installation Ease

An RV holding tank sensor’s installation ease is a function of the product’s type. For example, internal tank sensors require drilling through the sides of the RV holding tank at precise locations.

Most products need tank openings at the top, 2/3, 1/3, and bottom levels. However, a few brands observe the rule of quarters (top, ¾, ½, ¼, and bottom).

The principal concern about drilling is the risk of leaks. If the hole is too big, the tank sensor’s rubber plug might not form a tight seal around it. If the insertion point is too narrow, RVers might damage the probe if they force it inside the hole.

The good news is there is no need to drill if RVers only replace their existing probes. However, they must remove the old sensors first before inserting the new ones.

Meanwhile, external holding tank monitors are the most hassle-free to set up. You only need to apply an adhesive material in the correct position.

  • Cost Effectiveness

Although RV holding tank sensors do not cost a fortune, buying a complete kit might make more sense. Some brands offer a sensor, wiring, and indicator panel combo at an affordable price, sometimes less expensive than individual components.

However, cost-effectiveness goes beyond price concerns. Buying individual parts can cause compatibility issues. For example, wires from a different brand might not work as effectively with another company’s holding tank sensor or indicator panel.

These individually-bought components might have varying qualities and lifespan, impacting the system’s overall functionality.

Some RV holding tank sensors are also more economical than others. In such cases, RVers must examine the product’s quality construction and performance while identifying its differentiation from leading brands.

  • Brand Reputation

Some brands are more trustworthy than others, giving RVers peace of mind. For example, many motorhome owners trust RecPro, Valterra, and Camco to deliver high-quality holding tank sensors.

However, RVers must also keep an open mind about new market entrants by researching these brands.

Frequently Asked Questions (FAQs)


How do you install an RV holding tank sensor?

Installing an RV holding tank monitor system is as straightforward as mounting the electrodes or probes that come with the kit on the motorhome water tanks (gray, black, and freshwater).

RVers must read and understand the RV holding tank sensor wiring diagram to ensure its correct positioning and proper functioning.

For example, the orange probe must sit at least an inch from the holding tank’s top edge, while the green electrode must be about 2/3 from its bottom. The yellow lead must sit 1/3 from the lowest point of the tank, while the red wire connects to the DC power line.

It is worth mentioning that a single control panel can connect to three tanks – freshwater, gray, and black.

RV owners must measure the precise probe locations, marking them on the tank. Use a 3/8-inch drill bit to create a hole through the tank or whatever size the manufacturer recommends. Ensure to remove debris and burs from the opening.

Then, insert the sensor probes through their respective holes and fasten them with the accompanying hardware. Connect the wires to the electrodes and link the cables’ other ends to the indicator panel to complete the installation.

How do you fix an RV holding tank sensor?

Fixing freshwater, gray, and black water tank sensors requires determining the problem. Is there debris, a particle, or object covering the probe?

For example, a faulty RV black water tank sensor might be due to dense organic matter (feces, undissolved toilet paper, and organic matter) blocking it.

Gray tank sensors can suffer the same fate, although the most likely culprits are solid food waste, grease, oils, toothpaste, and bath products.

The best way to fix this problem is by filling the RV holding tank with water and an appropriate solution to sanitize the sensors. RVers can use cleaning agents specific for black tanks and Dawn dishwashing liquid for the gray holding tank.

If the problem persists after several cleaning sessions, you might want to check the wiring for signs of tampering, damage, or looseness. Loose wires are easy to fix. Unfortunately, damaged cables might require replacement.

If the cables look fine, it could be a sensor problem. In such cases, only an RV tank sensor upgrade or replacement will save the RV water level monitoring system.

Some motorhome owners recommend calling customer service to troubleshoot or test RV tank sensors before replacement.

Why are my RV tank sensors not working?

An RV holding tank sensor can malfunction for different reasons.

First, something might be blocking the sensor, like dirt or debris on the probe’s surface. It could be caked-on feces or toilet paper on the lead (in a black tank sensor system) or food debris, oil, grease, and bath essentials (in gray tank sensors).

Second, faulty RV waste tank sensors could be due to issues with the wiring from the indicator panel to the tanks. These cables are not as robust as conventional electrical wires. A loose wire can prevent the flow of signals from the probe to the indicator panel, making RV owners believe the system is not working.

Wire tampering and damage can also lead to signs of system malfunction.

Third, it is possible the indicator panel is not working, although the probes do. This component notifies you of the holding tank’s water level, whether it is full, 2/3-full, 1/3-full, or empty. A dysfunction in this device will make it impossible for you to know your RV holding tank’s content status.

How do you clean grey water tank sensors?

Start by closing the gray water tank valve and filling it with water above the “defective” sensor. Most RVers fill the tank to the top to clean all probes.

Get your Dawn Ultra dishwashing liquid and empty its content into the kitchen sink drain. Twenty ounces are sufficient, but more is better to optimize this product’s enzymatic grease-eating capabilities.

Leave the cleaning solution to work its wonder for at least eight hours or overnight before emptying the tank the following morning by opening the valve.

Close the valve again and refill the tank by opening the kitchen faucet and shower. Repeat this cycle of valve closing, tank refilling, valve opening, and emptying several times to rinse the system.

That is how you clean the gray water tank sensors.


Choosing the best RV holding tank sensors depends on an RV owner’s needs and preferences. Some brands have an excellent reputation, regardless of the sensor type they produce.

On the other hand, we must exercise caution when buying a holding tank monitor from an unknown brand. Specifically, examine a product’s materials, installation ease, and cost-effectiveness to ensure you get the best system for your vehicle.

Customer reviews can provide prospective buyers with real-world views about products. Moreover, RVers can read unbiased and comprehensive analyses, such as this article, to help them decide.

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