Shower Water Monitor Tracks The Dollars And Cents

There’s nothing quite as relaxing as a long, hot shower. This has the tendency of making the bather absent minded as to the amount of water being used, which can lead to excessive bills. [LiamOSM] built a device to monitor this instead, and calculate the cost, to boot. 

The device consists of an Arduino hooked up to a cheap flow meter sourced from Banggood. The sensor consists of a paddle wheel that sits in the water flow, fitted with a magnet. A hall effect sensor picks up pulses as the magnet spins, and counting these allows the flow rate to be measured. An HD44780 LCD screen is used to display the readings, controlled over I2C.

To avoid issues in the bathroom environment, the enclosure was designed to be waterproof. The LCD is mounted behind a clear plastic window sourced from vegetable packaging, and the button chosen was specially selected for its sealing grommets. We’d love to see a proper submersion test, but for the most part, it appears to be doing a good job in the bathroom.

If you’re interested in monitoring your water use as a household, you might find it possible to piggy back on the municipal meter.

24 thoughts on “Shower Water Monitor Tracks The Dollars And Cents

          1. That’s essentially what the timer does. Basically coasting on the heat in an insulated tank. Ideally a tank-less water heater would be the best of both worlds, but they’re more expensive, and one has to be careful in sizing for demand.

        1. I built that kind of device with 2 updates because I have 1 temp sensor in the flowmeter itself and also I put a solenoid on the entry: when the flow is detected and the temp is higher than 35 celsius (that means it’s a shower and we are not using the water to scrub the tiles), after 5 minutes the solenoid cuts the water for 5 seconds, a good reminder ! The second update is a safebaby feature: if the water temp is higher than 40 celsius (modulable), the solenoid cuts the flow. Babies and high temperatures are not friends !

  1. Our water cost is about double what i see in the photo above, and about 3x what it costs to heat it for showers (natural gas 93% efficient heater).

    I thought about making a real-time flowmeter rig like that to monitor our water use. In prep for that I did a (manual, pencil and paper, watching the meter) usage tracker in our house about a year ago, and found that by FAR the greatest water users were toilets, then laundry, then showers, then everything else. Surprisingly, the dishwasher uses very little.

    So I put 6 bricks in each of our toilet tanks, leaving just enough water to reliably flush. Total cost $7.04. It cut our total water consumption in HALF, saving $35 per MONTH. Payback period less than a week. Kicking myself for not doing it 15 years ago.

    I never did build the flowmeter though, and now that we are routinely below our city’s minimum bill amount (7000 litres/month) I don’t care about shower water use any more…

  2. What if this has the opposite of the desired effect? What, my shower was just 3 cents? Pfff…i can make it double. And I surely can afford one in the morning, one after work, one in the evening. This is insignificant in my daily costs.

  3. What if this has the opposite of the desired effect? What, my shower was just 3 cents? Pfff…i can make it double. And I surely can afford one in the morning, one after work, one in the evening. This is insignificant in my daily costs.

  4. It’s a nice idea, but as said it does not tell the total cost because it does not measure/calculate the energy needed for heating the water. Maybe you could add some temperature sensor(s) and some math to add this feature? However even knowing only the quantity of water is still interesting in my opinion.
    If you use your shower for cleaning things (like the filter of the vacuum cleaner) i wonder what _hot_ water does to the cheap sensor over time.

    1. I think calcium/lime/rust deposits would be a bigger problem than hot water.
      The flow meter as described, is a spinning magnet inside a plastic pipe with a Hall Effect sensor outside of the water stream measuring the rotations of the spinner.
      Whereas, hard water deposits could eventually jam the spinner.

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