Water Softener Level Detector Keeps You Out Of Trouble With Wife

Water Softener Monitor

Some households have water supplies that contain higher than desired levels of minerals. This condition is called hard water. There is nothing harmful about hard water but it does leave mineral deposits on pipes and appliances and makes cleaning a little bit more difficult. The solution is to have a water softener system which is basically a tank filled with salt that the household water passes through. This tank has to be refilled about every month and [David] was catching a little flak from his wife because he kept forgetting to fill it. He then set out to do what any great husband would do and built a Water Softener Monitor that reports the quantity of salt in the basement tank up to the living quarters.

[David] started thinking that he should test the salinity of the water to determine if salt needed to be added but after thinking about it for a while decided against it because any metal in that salty water would surely corrode. A non-contact approach would be to use an IR distance sensor mounted to the top of the tank and measure the distance to the pile of salt that slowly lowers as it dissolves into the water. In this case, he used a Sharp GP2D12 that can measure accurately from 10 to 80cm.

By itself, the distance sensor wouldn’t do much so [David] made his own PCB Board to hold all the necessary circuit components. The brains behind the operation is an Atmel ATtiny861 20 pin microcontroller. He’s got a lot going on and needed a micro controller with enough pins for all his bells and whistles. Besides sensing the height of the salt pile, the micro controller also outputs the salt quantity level via a 10 LED bar graph which is mounted in a wall plate. At first glance the wall plate looks like a standard light switch cover but it was actually custom cut on a CNC Milling Machine specifically for this project to ensure a perfect fit. Right below the LED bar graph is a photocell. The microcontroller only lights up the LEDs when there is a change in ambient light in the room, whether from a light turning on or a passerby casting a temporary shadow over the sensor. The LEDs will turn off after 3 minutes of non-activity.

81 thoughts on “Water Softener Level Detector Keeps You Out Of Trouble With Wife

        1. For what it’s worth, I agree that the lazy husband stereotype is being brought up here. I don’t think that means that the nagging wife isn’t being used also. They’re both part of the same tired narrative, and they’re both annoying. HaD could have framed this any number of other ways in the headline to avoid played out sexist cliches. I humbly offer “Water Softener Level Detector Helps Your Easily Distracted Ass Do Your Chores for Once”

          1. Or we could just move on.
            It is a really cool build but would suggest adding maybe wifi to it or some other rf system to allow it to talk to your home router that you have flashed with custom software. You could have it wake up once a day and tweet you if the salt needs to be replaced.

      1. It’s only sexist if you assume she’s going to nag because she’s female, and he’s lazy and will try to get out of the work because he’s male. The story didn’t do this, it just reported what happened.
        Remember, equality doesn’t mean you have to be a certain way, it means you can be any way, even if that way used to be the only way. She’s still allowed to nag, and he’s still allowed to be lazy. They just don’t have to be that way, they choose to.

    1. Go watch Avenue Q sometime, learn a lesson, then come back.

      I’m lazy, my wife is a nag. We both admit it and joke about it. Am I offended by this stereotype? Nope. I also fit numerous other stereotypes, do I get upset over them? Not at all.

      In short, if you don’t fit the stereotype, don’t complain, it doesn’t apply to you.

      1. THANK YOU!
        People are so sensitive about essentially nothing for no good reason.

        I wonder if any of these folks complaining are even married. If they are, I’m glad my marriage isn’t like theirs.

    2. Hi everyone,

      I am the author of the water softener article. Regarding the topic of sexism, I don’t want to wade into the volcano. However, I do want to tell everyone a story.

      I entered the HackadayPrize contest with the project “LoFi”. Given the time constraints and competitiveness, the experience was expensive, emotional, and exhausting. (It was also thrilling.)

      For three months, nearly every waking leisure hour was dedicated to working on the contest. A reasonable person would expect a spouse to feel neglected and to lash out. Instead, I would come home from work to find various containers that she had picked up from the store in hopes that any might be repurposed as project cases. Newly arrived boxes from eBay and Mouser would be neatly stacked on my desk, without her so much as a querying as to the cost or need.

      Before the contest rules were changed, the finalists were going to be flown to Germany. My wife quickly got my passport into the renewal system. When the introvert in me sheepishly suggested I would not attend, she got a passport for her to accompany me. She felt that if I were fortunate enough to make it into the finals, we had an obligation to make the event successful. To that end, she would help me to do so.

      The finalists were announced two weeks ago, and I did not make it. When I arrived home, there was chilled champagne and my favorite dinner. She wanted to celebrate the accomplishment of entering a contest and giving it my all.

      That’s my everyday relationship with my wife. There are rarely public contexts appropriate to talk about such things, so I am taking advantage of this opportunity to tell the story here. I am blessed to have her in my life.


      1. David,thank you for sharing your projects with us, and thank you again for sharing this story. I’ve enjoyed reading your books and articles for years. Your wife sounds like a great person – it’s always great to hear about families supporting each other in their passions!

      1. Agreed… this is why we have a calendar on the kitchen wall on which we write up such things. Disappointingly low-tech, I know, but no Arduino required nor does it sip watts.

          1. It’s best to let the salt level go all the way down from time to time, or you’ll risk the formation of a “salt dome” at the top line of the brine solution. The recharge cycle will still run, but your salt level won’t go down, and your tank will never recharge.

    1. That is a possible solution. Then again, a statistically significant portion of the female gender still prefer to complain you didn’t put the toilet seat down after use, rather than taking two seconds to check and put it down themselves if needed.

      Increase the difficulty of the task, like topping off a reservoir with salt, and the portion of females who prefer to nag a male to do it only increases. Even the female was already next to the reservoir and could have accomplished it in under a minute, she might stop to go find you at the other end of the house, chew you out for a couple of minutes, and return to what she was doing *next* to the reservoir. Then you have to walk to the reservoir, perform the task, and go back to what you were doing. No matter that what could have taken one person one minute, took two people 10 minutes of combined time instead. (But heaven help you if you try explaining that logic in an attempt to change her behavior and improve household efficiency.)

      Sorry sensitive folks, but there’s a bit of truth behind every stereotype, regardless of gender. Change the truth first. Only then is getting rid of the stereotype completely justified. If the stereotype applies to others, but not to you, don’t get offended. Feel a bit of well-deserved pride instead.

  1. I agree with previous posters on the HaD stereotypical sexist editing part. I would rather read about the device and its making process.

    Cool hack nonetheless. I like the finished look of it, as well as the service design aspect of how it works. The user interface of a led bar graph display well thought. Non-contact level sensing is well chosen for the application.

  2. Your water does not flow thru the brine tank. It’s brine flows thru the exchange medium to remove minerals that it picks up during normal flow. These softeners are banned in some places as all that salt ends up in the sewer or worse in your septic tank.

  3. Cool project that serves its purpose, but come on an old lunch meat container instead of a simple plastic old work box to house the LED bar graph circuit in the wall. I wish I had a mill, but I could have measured and cut that plate in 5 minutes with hand tools. I just have issues with someone who has great ideas and skills to build this type of circuit yet gives it a rigged up look.

  4. All issues of indignation over cultural correctness aside, I think this rates pretty well as a proper hack:

    *It does something unusual, using methods and devices that other readers can use and adapt to their own projects.

    *He documented the project very well, including “suggestions for next time” and potential failure areas.

    *He (apparently) had fun doing it.

    1. Yeah. It is a well thought out project and a good write up. He addresses several problems like corroding electrodes and then tells you how and why he did what he did. Some neat extra features like the closet light sensor as well which I wouldn’t have thought of but are a great idea.

    1. Be careful though or you’ll reach a point where you’re the overlord of a vast robot army and have a salt mine :D Of course, that would completely solve the issue of filling the water softener salt container…

  5. Wow at these comments. First let me say I think this is a great build and I’m impressed with the end quality.

    For those of you arguing about sexism turn down your sensitivity. Honey dos are a very real thing on both sides of a marriage.

    For the elitist I had to check the replies multiple times to make sure I wasn’t missing the sarcasm. He had a problem, came up with a solution, and made it look good. What more do you want? Not everything needs smd components and printed circuit boards.

  6. I could have built something with the exact same function but without an engineering degree. All the sensors and outputs are sold at plumbing supply stores and use low tech methods. Float sensors, relays, thermostat wire. You know, simple stuff.

    I also find it amusing that dude went out of his way to use a CNC machine when the same job could have been done with an x-acto knife and a jeweler’s file. Maybe a Dremmel if he has steady hands and some skill.

    1. Actually, the brining tank is normally dry, and the salt reservoir is kept in it. During the recharge cycle, a measured amount of water flows into the bottom of the tank, mixing with the lowest pieces of salt to form a brine mixture, which is then circulated backwards through the exchange tank to recharge the resin beads (replacing the trapped positive magnesium and calcium ions with negative sodium ions), and routed to the drain.

      There is no place to mount a typical float switch, as the water doesn’t rise above the top of the salt until the reservoir is almost empty, and even if it did, the water doesn’t remain in the tank unless it’s recharging. Automatically measuring the top of the pile of salt is difficult with a mechanical system, as the salt pellets, crystals, or rocks do not act like liquid. The sometimes damp crystals stick to everything, and will jam and/or corrode everything they come in contact with. About the only way to reliably measure the salt is with a non-contact method. That takes electronics. It’s not “simple stuff”.

      1. I would replace the float with a weight so it wasn’t affected by the water and instead sit on top of the salt. When the weight hits its cut in point it would close the circuit and send a signal to the output. A light or something near the oil burner switch at the top of the basement stairs.
        Culligan sells a device to handle the problem that will email you a reminder.
        But instead of doing all that I just check the salt level every week and keep salt on hand to fill the water softener. Nice and easy.

  7. Nice project, except this is not how water softeners work. Water softeners use glass beads coated with sodium ions to attract the hard water deposits. The salt is used to remove the hard water deposits from the beads. So the beads are periodically rinsed with the salt water, then fresh water.

    The article mentions the household water passes through a tank of salt water. This would corrode your pipes and fixtures, which would be worse than the hard water deposits. The household water is run through the glass beads, which remove the hard water deposits.

    1. I came to read the comments, thinking people would complain about this inaccuracy which you corrected. Mean time they complained about a nagging wife? Damn, my wife nags too and I’m proud of it. And I’m lazy and try to automate everything and she’s proud of it too.

      Oh wait, now I’m hijacking the actual comment I want to see here and turn it into a debate of sorts. These people are getting to me. Ugh. Save yourselfs!!!

      (P.S. [David], nice build)

    2. Thank you for this. I admit that I was a little confused by the article’s description as adding more dissolved minerals to the water seemed to be the exact opposite of the desired effect.

  8. The headline of this post demonstrates perfectly why women either refuse to enter the engineering fields or are driven away by pervasive (and often aggressive) misogyny.

    Rich Bremer (or whoever wrote this headline) needs to grow up.

      1. Apparently you don’t understand the meaning of the word “example.”

        It’s not just *this* headline. This headline is merely one of a multitude of things, both large and small, that contribute to creating an environment in the tech industry that is very hostile to women.

  9. @Trui
    Come on, you know what he meant. The headline doesn’t exist in a vacuum. It’s emblematic of the pervasive obnoxiousness in the field. Being implicitly (and sometimes explicitly) told literally every day that you do not belong in the field wears a person down. Then when a woman complains about it people imply they don’t love the career enough, or that they’re think skinned.

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