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Spring thaw drainage dc pump Answered

Every year we get large puddles around our property in low lying areas. Our front sidewalk also dips down at our steps and gets a huge pool. I could shopvac the puddles but the problem is they REFILL slowly but consistently until the grass dries out during the spring thaw. This is a big problem because in the morning these large puddles are ICE and are slippery as anything. Then they thaw during the day and the cycle repeats - for a month or so.

So I took an old cheap craftsman tool box and put in a 12v5A battery and a 12v5A pump. The pump uses 3/8" clear hose that you'd see coming from a condensate pump. I put in a 20 mesh filter reservoir thing to keep out small particles from the pump.

I ran it and WOW - not only did it work perfectly but even my wife thinks it is "cool". The pump works at about 1 gallon a minute. I purposely did NOT want a high capacity pump. I wanted to move the water slowly and allow it to drain back in. Also if you move water slowly you have way less problem with sucking in leaves, etc. It just quietly does its thing and in about 1/2 hour the puddle is gone. The problem is - overnight the puddle comes back.

So I'm going to wire in a dial to slow the rate of flow down.

I'd also like to make a water sensor switch. The water has very little salt in it so no electrolytes to make good current. I tried zip tying two wires to the mouth of the intake and wiring them between the battery and pump positive side. No dice.

Does anyone know how to make a water activated switch that would work here? If I could get that done I'd have both flow rate and auto on/off. Sweeeeet.


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Jack A Lopez
Jack A Lopez

2 years ago

I suggest using a multimeter to measure how much current flows through your water sensor.

I think most people do not know how to measure current with multimeter, so I always include this link:


Then, once you have realistic estimate for how much current your conductance sensor gives, use some combination of op-amps (or comparators), transistors, and relays, to sense that current signal, and switch a much larger (~5 A?) current to the pump.

The reason I suggest an op-amp (or comparator) is because those have crazy high gain, and it desirable to have a circuit that switches the pump all-the-way on, or all-the-way off.

If one were naive about this sort of thing, he or she might expect that is what would happen naturally, but it is not.

Sort of the worst thing you could do, is try to switch current to the pump through a single transistor, but have it wired in such a way that the transistor gives a proportional response to the current it feels from the conductivity sensor, so that there are circumstances in which the transistor gets stuck in a state partially switched on, a case in which the transistor itself is dissipating power, while at the same time the pump is stalled with a too low current flowing through it.

Hysteresis is another good quality for a switch to have, so when it trips on, it stays on, at least for a short time, because swtiches that go wacka-wacka-wacka, turning on and off several times a second, are annoying too. Another reason op-amps are handy, is because there are some tricks with op-amps that allow you intentionally add some hysteresis to your circuit. Perhaps the same thing can be done with transistors, but I am less familiar with transistor tricks.

By the way, I am wondering what you mean by, "wire in a dial to slow the rate of flow down?" I am curious about that. I mean, I know about ways to throttle power to an electric motor. I am just wondering at the hardware thing you're calling a "dial," and if that thing is what I think it is.


2 years ago

You could also start by adding some drainage pipes in the ground.
Have them run to the lowest part of your property or area in question.

For the sensor I still say mechanical float switches work a treat.
Similar story if you use two metal rods (preferably stainless) and some simple electronics - look for circuits in regards to bath tub leveland general water level alarms.
Last but not least you can use capacitive sensors, just hand it in a dry spot above the water line and once the water comes to close it activates your pump.