Homemade Hot Water Shower Might Shock You

DIY Hot Water Shower

[Stephen] doesn’t have the luxury of readily available hot water in his apartment, and since he’s just renting he didn’t want to buy one of those instant powered units, so he decided to go ahead and build his own!

He’s using a submersible 1000W immersion heater in a 2.5 gallon water container which has been mounted high up in his bathroom to let gravity do the work for actual shower. It’s not quite an instant shower unit as the water needs to heat up like a kettle before being used — this takes about 4 minutes to hit the optimum temperature.

The current shower head installed drains the tank in about 2.5 minutes, which might not seem like much time for a shower, but let’s be honest — we could all probably cut back our shower time and save some water for the environment! Something one of our Hack a Day Prize entries is hoping to solve through music!

Oh and the shocking bit? Don’t use the water when the heater is on…

68 thoughts on “Homemade Hot Water Shower Might Shock You

  1. Very nice! Although what apartments don’t have hot water? :-P

    If my math is correct, 1000W could raise the water temp in a 1.5gpm low flow shower head by about 10C (~100mL/sec, 1C/L/s). I wonder if that would be enough to turn it into an on demand heater – provided the “shock” problem is solved of course.

    Based on his accent I’d assume he’s somewhere with 240V service, which means you could get a 3000W immersion heater, which would allow 30C raise on a low flow shower head, which should be more than adequate for continuous use.

    1. I don’t know a lot about apartments on the continent. But in my limited world travels, I’ve encountered a number of showers that only supplied unheated household water vline.
      (These may have been in the Tropics, where the “Cold” water is lukewarm at best.)

    2. While he does have a UK accent, he mentions in the comments, he’s not living there but currently in the Philippines (which also ties in with it not looking like any UK fittings or setup). It does still happen to have 220V mains although I suspect he’s limited to what he can get (he’s not even got an RCD as he couldn’t find one in the local shops).

      1. No big problem with that. As long as the electric installation is correctly grounded, no big risk of shocking oneself. And risks are the same as having a gas leak in a central heater.

        1. Grounded? Waste of cupper. And glass insulation, that would work cuz the heather’s switch is: two contacts for which the water closes the circuit. And yes, pretty much every on in brazil have it the 220V and the 125V ppl. Althoug some have gas heaters too.

      1. In fact, I was searching about news of anyone dying while using an electric shower, as I’ve never heard about any, and found news about people dying with gas showers, but none with electric showers.

        1. Yeah, they’re the de-facto shower unit in South America, and I wouldn’t be surprised if in a large part of Asia too. Boilers are still only found in the new homes of the wealthy – they’re expensive! Plumbed gas is also a rarity, people usually just have a gas tank attached to the cooker.

          It took me a while before I had the balls to use one of these showers, and I have admittedly experienced 1 or 2 mild shocks (don’t play with them when they’re in use!), however I’ve never heard of any serious injury or death resulting from them & they’re used by millions of people every day, so…

          Remembering the MythBusters episode when they tried to recreate the guy getting zapped whilst pissing against a live railway track, water breaks into droplets *very* quickly, so risks of conduction from the shower-head are pretty much 0.

          1. Yep I lived in Brazil.. for about 4.5 years and used both the metal model and the plastic model (the metal one shocked me a tad when adjusting it a time or two as well…)

            We also had solar water heater panels on our roof which are fairly common assuming you aren’t quite poor, unfortunately quite a lot of people are too poor to own one most people do have a heated shower head though and thier water box will often be on the roof to absorb heat from the sun.

    1. I’ve used one of those in South America. You’d get a little buzzing sensation if you touched the bars on the window, but it wasn’t even uncomfortable. And being that the electricity can flow around your body through the water and into the plumbing, pretty sure there’s not much of a concern there, maybe? Anyway I would have risked electrocution, incineration, and probably dismemberment for a hot shower.

  2. 2.5 minutes? Solution: “Navy” shower; 1 minute on, shut off and suds up, then another minute on to rinse off. The suds time would probably allow for adequate (sp?) heat recovery.
    On a similar note, I remember seeing an ad (years ago) for a shower based water heater. The ad copy said it was like “European showers!”. That turned me off immediately, the showers I’d used in London, Rome, and Israel (they consider themselves “European”) was akin to getting peed on…

    1. Heck yeah, the old armpits crotch and feet :) Top n tails will get ya through. There is absolutely nothing on this earth though like the first shower you take after camping/hiking. So nice…

    2. Not on that short 1 minute timeframe. But of course I shut off the water when I apply the soap/shower gel. I want to distribute it evenly on my body before it gets washed off. Otherwise most of the soap would go to waste, before it even reaches the skin.

  3. Wow, I’m happy to see my project posted here :D

    I had considered one of those instant electric shower heads but I just don’t have the guts to use one of those! Plus the ones I saw being sold still require a 30 amp circuit and I wanted to stay within a 10-15 amp circuit.

    I posted a comment on Youtube a short while ago about what happens if you touch the water while it’s heating. It gives you a tingle similar to those exercise belts that supposedly give you abs by shocking your stomach. I wouldn’t recommend touching the water, but in my experience it wasn’t deadly.

      1. I do agree that a GFCI / RCD would be a safer choice than a standard circuit breaker. If they were available locally (Manila, Philippines) then I would have bought one.

        These immersible heaters are pretty common here and most people have experienced the ‘tingle’. But as you suggest, there’s no point taking a risk when there re safety devices out there that can be used.

        For now I’m just making sure to turn off the breaker before I shower. But ultimately I’ll order a GFCI plug/socket/breaker online and use that, just incase I ever forget to turn off the breaker :)

        1. Steve, you’re dancing with death here. I’d never use this. There are plenty of immersion heaters with metal housings, which you can ground. At a minimum, I’d recommend you do that. And the breaker box in the bathroom scares me, too. This would never pass muster in the US.

          1. I have seen other immersion heaters which are similar to those used in regular home water heaters, they’re metallic looking (coil or straight) and are insulated so you can safely touch the water while it’s turned on. I could use one of those and I could indeed look for one which has the option of grounding.

            But would that really be any safer than using this type of immersion heater with a RCD/GFCI socket?

            From what I’ve seen of power showers, they’re essentially the same thing except they use a higher wattage heating element and have an RCD mini breaker built into the housing.

            Remember that I’m turning off the circuit breaker before I shower.

          2. The *much* safer way:
            – get an immersion heater with a grounded metal housing (3 wires coming off it). Run it through a GFI breaker. The grounded metal housing means that AC has to go to ground (which would blow the breaker) before it gets to the water. The GFI handles the case where the ground on the housing opens up…through corrosion or whatever…and AC gets to the water (which provides a path to ground through the drain and trips the GFI). If you can’t find an immersion heater with a grounded housing, get a cartridge heater like this:
            and install it into a hole drilled in a block of metal (aluminium works well and is east to machine. Ground the block of metal. Put the metal block in the water. This has the bonus of not requiring you to immerse the heater wires in the water (only the grounded block of metal goes in the water).

            The above design is much safer than what you have now. ANY “tickle” indicates that you’re passing AC current through your body. This is never a good idea. In fact, you’re only a few milliamps away from death. Someone else posted about the soldier who dies in Iraq from a poorly designed shower/heater system. I can’t emphasize enough how dangerous the original design is…if that breaker were to be turned on while you were in the water, it would only be luck keeping you from electrocution.

    1. I fear that would not work. At lest not with a 30mA GFI:-) These devices rely on a “fault” current which goes into the water piping and into the ground wire which is immersed into the water at the output side.

  4. There are many electric shower heaters out there which is a proven technology (scary as hell but works!). This project should also add an automatic shut-off valve for the water (a simple toilet float would do).

  5. “we could all probably cut back our shower time and save some water for the environment!”

    Consumers shaving a few gallons off their daily routine won’t save the planet while manufacturing and the ag industry are wasting hundreds of thousands of gallons a day.

    1. let’s all save some energy by driving to the local building supply store, buying an inefficient electrical appliance, and then consume even more electricity than you would consume if you bothered to learn some social skills and share with your neighbors.

      Yes indeed the answer is to ignore your neighbors and go it on your own. That’s the tickd.

          1. many small farms would require much more people to work in farming, food production. I am glad I don’t have to do that and be able to work in electronics.

  6. Heated shower heads? 220 on a hose to the shower, no way. Stationary mounted showers suck and waste water! Would you spray a car with paint by rolling it under a “spray head”?
    The first place I spray is the bottom, not my head.
    Like the fine in California for using a hose without a nozzle there ought to be a law against having to use 2 handles to throttle the flow while soaping and having to readjust the temp after messing with the setting to throttle the flow in the first place. A single valve on the mixed line is mandatory.

    1. I want (and have) a shower with a hose but also a wall hook. I want to be able to have both hands free while showering my upper body and to move tho shower head to wash other body parts. In my opinion a handheld-only shower is wasteful, because you need much more time (water flow) when e.g. you have to wash your hair one-handed.
      And yes, a single lever mixing valve is also a necessity. I can not understand the brits which keep the two separated taps.

    1. Ahh, a trip down memory lane!
      These were pretty popular (although forbidden) in the East German Army to quickly heat up your cup of coffee. Or a similar design made from round metal disks held together (and separated) with a plastic snap button – lovingly called “UFO”…

    2. I really thought about building such a contraption at the campsite last week when we ran out of butane to make coffee. We had an electrical supply but used it only for the fridge box as I did not have any electrical cooking top or water heater. But it was on the last day anyway.

  7. If he’s in the sunny tropics, a long coil of black plastic tubing in the sun on the rooftop should work as well and offer no shock danger.

    I spent the summer on an island in the Caribbean. Since it never freezes there, water pipes are often run on the surface. One place I stayed, I got about 15 seconds of hot water from a pipe before the water turned the usual lukewarm.

    1. AHA someone finally posts the winning way to do this.

      This technology is also quite effective in temperate climates.

      Really one only needs a few seconds of hot water to rinse off the soap.

      1. You are fooled by the hardness of the water. Rinse in soft water and you will feel slippery, that is the soap which will take much more rinsing to remove. Five times or more as much!
        Hard water covers up this effect, the soap is still on your skin. Worse yet, detergents in the hair follicles that don’t get rinsed out completely are a cause of thinning and balding hair.
        Rinsing is important don’t skimp on it.

        1. I noticed this when I use an improvised shower with a small pump from the rainwater tank in the garden. Much more difficult to remove the soap. In harder water, the soap chemically reacts with the hardness, so it’s washed off more easily. I don’t believe, that it stays on the skin.
          The temperature is just what the water in the barrel has, no heater.

  8. A little dicey in terms of safety, but I like the utilitarian features and it does seem to solve a problem in a terse environment. I like the stick float for capacity measurement. Might I suggest for future improvement a thermal sensor-based (i.e. thermistor) heater shutoff rather than using time for a more consistent temperature. Also, a magnetic stirrer system using an encapsulated stir bar and an exterior magnet on a small motor would solve the manual agitation problem. Very nice job, though.

  9. There’s a cultural solution to this problem I learned in Nicaragua. Instead of a running water shower just heat the water (about 3 gallons) however you want and dump it into a 5 gallon plastic bucket. We usually used a kettle and dumped about two kettles’ worth into about 2 1/2 gallons of room temperature water dipped using the bucket straight in the well, or from rain catchment. Take the bucket and a dipping bowl to the shower with you. Dip with the bowl, pour on yourself, and wash. It floods your hair completely, which really makes shampooing easier than a slow shower head (and with wonderful results using rain water). Also, if the water is still cool then slide your other hand over the part of your body you are pouring water onto as you pour. Your body will naturally register this as much warmer, and even unheated water (at room temperature) won’t stress you. Also, do your hair or head first, just like going head under first in cold swimming. Best of all, you’re back to worrying about slipping and falling, not being electrocuted. Plus, you know exactly how much water you are using so you can adjust as you go. Carry in 4 gallons for a “long shower” and still be saving the planet! Easy to try right here in the US.

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