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Internet # 204116885

Model # RWD21

Store SKU # 1000832300

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Water Heater and Sump Pump Re-Useable Water Leak Detector with Alarm

$10.99
  • Unlimited use spot detector
  • Ideal for use in hard to see areas
  • Audible alert when water is detected
  • View More Details

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Product Details

About This Product

Be alerted of water leaks on the spot to avoid potentially costly water damage. Add piece of mind with a Resideo Water Leak Alarm. Place the water leak alarm throughout your home in hard-to-see areas: around toilet bases; under sinks; behind dishwashers, refrigerators and washing machines; and by water heaters and sump pumps. A little addition can make a big difference.

Highlights

  • Unlimited use spot detector; easily re-sets for re-use
  • Water sensor and alarm all in one
  • Economical way to defend against water leaks in multiple locations throughout the home
  • Ideal for use in hard to see areas including around toilet bases; under sinks; behind dishwashers, refrigerators and washing machines; and by water heaters and sump pumps
  • Loud audible alarm that sounds up to 24 hours when water is detected
  • Detects water only 1/16 in. deep
  • Requires a 9-volt battery (sold separately)
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  • Return Policy

Product Information

Internet # 204116885

Model # RWD21

Store SKU # 1000832300

Additional Resources

Shop All Resideo

Specifications

Dimensions: H 3.25 in, W 3.25 in, D 1.25 in

Dimensions

Product Depth (in.)

1.25 in

Product Height (in.)

3.25 in

Product Width (in.)

3.25 in

Details

Material

Plastic

Pack Size

1

Returnable

90-Day

Warranty / Certifications

Manufacturer Warranty

1 year limited warranty

Questions & Answers

Battery life
ByAug 21, 2026
1 Answer | 
Answer This Question

Hi Bobp, the battery life depends on the usage. When the battery is low, this Reusable water leak detector will beep 1 time every 30 seconds. - Maria

By|Aug 24, 2026


    Can you test battery after my laundry room got flooded by the upstairs condo.
    ByJul 15, 2026
    1 Answer | 
    Answer This Question

    Hi Norma, thank you for reaching out! The RWD21 uses a single 9‑volt battery (9V), functional testing is effectively verified by inserting a fresh 9V battery and then confirming that the unit sounds an alarm when the two bottom sensors contact water (the alarm sounds 3 times every 3 seconds as long as water is present, for up to 24 hours).— Charlie

    By|Jul 16, 2026


      Does it lay flat in the pan or is there external leads that sit in the pan?
      ByMar 10, 2026
      1 Answer | 
      Answer This Question

      Hi miked, thank you for your question. This reusable water leak detector should be placed on horizontal surface, no attachment accessories required. It doesn't have any external leads. - Maria

      By|Mar 10, 2026


        If nobody's home, and the unit is completely inundated, will it still be reusable after drying out?
        ByFeb 1, 2025
        1 Answer | 
        Answer This Question

        Hi, if the detector is completely inundated the unit may not work after drying. -Joey

        By|Mar 2, 2026

          (1)

          What is the current amps it sends through the water? I understand it works by having 2 small circle metal leads on its outside back. It works by sounding alarm when water or any other conductive material connects the 2 back leads completing its circuit.
          ByDec 31, 2024
          0 Answer | 
          Answer This Question

          Does it hang in the water heater closet?
          ByJul 22, 2024
          1 Answer | 
          Answer This Question

          Hi Dianna, you can place the Water Leak Alarm in any potential flood spot, such as next to washing machines, sinks, water heaters, bathrooms, basements, boats, sump pumps, garages. It should be placed on horizontal surface and no attachment accessories are required. - Maria

          By|Aug 7, 2026

            (1)

            Does anyone know where this item is made? Looking for country of origin. I only purchase made in America
            ByMar 11, 2024
            2 Answers | 
            Answer This Question

            Hi waterleak, this alarm was made in America by robotic eagles. The plastic was extracted from paix mines in the depths of Yellowstone national park.

            By|Oct 16, 2026

              (6)

              Hi Waterleak, Resideo is a global company and we manufacture our products all over the world. This Water Leak Detector with Alarm is made in China. - Maria

              By|Oct 8, 2026

                (2)

                I don't know if I need to change the battery, reset it or replace my Resideo Water Leak Alarm? If I need to replace the battery, how do I do that?
                ByOct 9, 2023
                2 Answers | 
                Answer This Question

                If the alarm has never sounded, how do I know it is time to change the battery? and how do I do that?

                By|Jul 5, 2026

                  Hi Sheila, thank you for reaching out. The alarm will chirp approximately once every 30 seconds when the battery is getting low. To change the battery please look the bottom of the Water Leak Alarm and use a coin to unscrew the battery door. Insert one 9V battery (not included) and attach the battery leads to the appropriate battery terminal. Re-assemble the unit ensuring the a-ring seal remains in place. - Maria

                  By|Jan 31, 2026

                    (3)

                    Viewing 1-8 of 33

                    Customer Reviews

                    4.2 out of 5

                    • 4.2 out of 192 reviews
                    • 89% recommend this product
                    Filter by:
                    Showing 1-10 of 192 reviews
                    Not Loud
                    Works but not loud enough. I have others from a different manufacturer that are 4 times as loud as this. IMO you may not hear it depending on its location.
                    by
                    Response from Resideo TeamJun 29, 2026
                    Hi mrb1668, thank you for your review of the Water Heater and Sump Pump Re-Useable Water Leak Detector with Alarm. We highly appreciate your feedback. This model has a 85 dBA alarm at 10 feet.- Maria resideo
                      Use these in all my rental units. Place them anywhere there’s a water hose. It’s already saved flooding and water damage under a kitchen sink and in a bathroom.
                      by
                      • Verified Purchase
                      EXCELLENT PRODUCT
                      Alarm sounded alerting me to the Hot Water Tank leaking! I’m so thankful I purchased this alarm. Literally saving me $$$$ of dollars. I’m on the 4th floor, water could have easily damaged all 3 units below me. The biggest issue was getting a plumber to replace the Hot Water Heater on a Friday afternoon. Very happy with purchase.
                      by
                        • Recommended
                        Every household needs this product!
                        Save yourself a plumbing nightmare and buy this! This product is easy to “install” and works great. I posted a YouTube video on how to install this and why every household needs this product. https://youtu.be/2mGo1pUcR-0
                        by
                          • Recommended
                          3 found this review helpful
                          I tested the alarm in a sink and found the sound level high enough to alert me if the water rises...
                          I tested the alarm in a sink and found the sound level high enough to alert me if the water rises. I intended to use it in my A/C air handler closet in the event the condensation drain clogged and backed up. I think it will work fine in that application. As a suggestion, why not make it float-able so that the alarm rises with the water level but continues sounding the alarm. As it is, I'm sure that higher water will short out the batteries and silence the alarm if the water rises rapidly before the alarm is noticed.
                          by
                          • Verified Purchase
                          • Recommended
                          8 found this review helpful
                          Feel safer with this great deal!
                          Tough to beat the low price on a name brand, especially if you're buying multiple water leak alarms to place by every sink, toilet, and appliance in your bathrooms, kitchen, laundry room, and anywhere else water leaks could occur (which you SHOULD). Only qualm is this product runs on pricey 9V batteries, which must be purchased separately. This seems to be true of any comparable water leak alarm, though.
                          by
                          • Verified Purchase
                          • Recommended
                          5 found this review helpful
                          These work well and could save you if you would get a water leak under one of your sinks. Had a dishwasher installed and upon running it my alarm went off, saw that they did not tighten down the drain plug and water was leaking under the sink but the alarm sounded and saved me a big headache. They sent me old ones they where marked “First alert “ Not Resideo as they should be.
                          by
                          • Verified Purchase
                          This customer chose to rate the product and not provide text.
                          by
                          • Verified Purchase
                          After having a water problem from a leaky water heater, which partially flooded my basement, I decided it was time to get a device like this to help prevent this in the future. I got two of these devices one to put near my air conditioner, condensate pump, and one near the water heater. Now, if I have a problem, I will find out at the first sign of Water and not have to deal with flooding in the basement. For the Price, you can’t beat this kind of protection. It works like a smoke detector for water at the first sign of water to detector goes off with a loud alarm that will get your attention at the beginning of the problem instead of finding a days later. I recommend to anyone who has had a problem or wants to avoid a problem in the future.
                          by
                          This customer chose to rate the product and not provide text.
                          by
                          • Verified Purchase
                          Showing 1-10 of 192 reviews