Relay assembly close-up.

How to Make Your Septic Alarm Smarter 11


Last week, I was working in my back yard when I noticed that the big red light on top of my septic system control box was lit up. That light is triggered when one of two alarm floats (in either the main effluent pump chamber or the clearwell pump chamber) detects that the fluid level in the chamber is too high — which could mean a failed pump, failed wiring, or clogged septic lines. But what caused greater alarm (pun intended) was the fact that the buzzer in the control box, which should have been loud enough to hear from inside the house, wasn’t making any sound at all! The buzzer had failed, and because the septic control box isn’t visible from the house, I had no idea how long that red light had been on.

I removed the lid from my main pump chamber. Everything looked OK. The alarm float in that chamber was hanging down, telling me that wasn’t the cause of the red alarm light.

I opened the lid on the clearwell, and saw that the water level was high enough to trigger the alarm float. Something was wrong in the clearwell!

How a Septic System Works

For those who might be less conversant in septic parlance, here’s how a standard sand filter septic system works (for those who already know this stuff, feel free to skip down to the next section):

A standard sand-filter septic system.

A standard sand-filter septic system.

All the toilets and drains in your house empty into your septic tank. Some solids sink to the bottom and turn into “sludge.” Some solids float to the top and turn into “scum.” The remaining liquid in the middle is called “effluent,” and flows out from the septic tank into a pump tank (also called a “pump chamber”) to be pumped out to the “absorption area.” And absorption area could be either a drain field or, in more complex systems, it could be a sand filter system. Here’s a closer look at the septic tank and pump chamber portion of any septic system:

Standard septic tank and pump chamber.

Standard septic tank and pump chamber.

Notice that the pump chamber houses a pump (duh) with at least two floats: when the lowest float rises up, that tells the septic control box to turn the pump ON because there’s enough liquid in there for the pump to do its thing (pumps should never run dry). When the pump empties the chamber enough for that float to hang down, the control box turns the pump OFF. If higher float rises up high enough, that tells the septic control box that the fluid level has gotten too high, which triggers the light and buzzer to tell you something’s wrong (unless your buzzer is broken, of course).

Many systems just have one pump to worry about, but because I also have a sand filter, I have a second pump to worry about. A sand filter system works like this:

Sand filter system detail.

Sand filter system detail.

In the above image, #1 is the septic control box and #2 is the combined septic tank and pump chamber. We’ve covered those already. The entrance to the sand filter is #3, where effluent comes out of the pump chamber and into the sand filter, then trickles down through sand and gravel until it collects and drains into what’s called a “clearwell,” which is #4. The sand filter pump in the clearwell then pumps the processed effluent out of the clearwell and into a drain field. Like the septic pump chamber, the sand filter pump in the clearwell has floats to control the pump and trigger the alarm if the fluid gets too high.

What Caused my Sand Filter Pump to Fail?

Back to my story, when I looked inside my sand filter’s clearwell, the fluid level was high enough to trigger the alarm. Luckily, I’d noticed the red alarm light on the control box in time, because the water level in the clearwell was just barely high enough to raise the alarm float — meaning my system probably could have continued to work for a few more days before causing any serious damage… especially if we were careful not to use too much water in the house. Manually actuating the ON/OFF float in the clearwell revealed the problem: Hydromatic SKHD150M2 1.5 HP cast iron monster of a sand filter pump had failed. I could hear it trying to work, but it just sat there whirring.

Ouch. That’s a $1,500 pump, dead after 5 years.

Further investigation revealed the likely source of the failure: the ON/OFF switch for my sand filter pump was a vertical float switch, and that type of float switch is prone to get stuck in the ON position (corrosion on the center shaft is the usual culprit). Here’s what a “vertical” float looks like:

Vertical float switches are prone to failure in septic systems.

Vertical float switches are prone to failure in septic systems.

If you have a vertical float in your septic system, I recommend swapping it for a more reliable “tethered” float immediately, which works like this:

Tethered floats are more reliable.

Tethered floats are more reliable.

I have meters in my septic control box that count the number of times each of my septic system’s pumps have turned on, as well as the number of hours they’ve each been running. Checking and comparing those two meters showed that my sand filter pump was turning on enough when compared to the septic pump, but that it had been running for considerably more hours. This bolstered my suspicion that the sand filter’s vertical float had repeatedly gotten stuck in the ON position – meaning it had just kept running when clearwell was empty. The vertical float probably worked sometimes, and the pump has a built-in thermal protector that shuts itself down when it gets too hot, but eventually the pump had burned out.

I removed the pump and float tree from the clearwell. To lower the high water level, I grabbed my Simer M40P mini-vac pump that I use when flushing my water heaters (it’s the best pump available for $90), ran an extension cord, connected a lawn sprinkler to the pump, then pumped the clearwell water to the sprinkler to irrigate a nearby brown spot in the lawn (courtesy of a record hot Seattle summer). After being treated by the sand filter, the water is clear, has no smell, and while it’s not advisable to drink it, there’s nothing wrong with watering your lawn with it… as long as nobody rats you out to the county health department. 😉

Emptying the clearwell with a Simer M40P mini pump.

Emptying the clearwell with a Simer M40P mini pump.

I was able to get my pump rebuilt for $350 (a fraction of the $1,550 cost of a new one) and pick it up only two days later. I installed it myself with a tethered float in place of the vertical ON/OFF float. The freshly-rebuilt pump quickly drained the rest of the clearwell water back down to its normal level, and the tethered float shut it off like a boss.

Problem #1 solved!

Fixing the REAL Problem

With the pump working, I purchased a replacement alarm buzzer for $35 and got ready to install it in place of the failed one. But that got me thinking: had I not been lucky enough to see the red alarm light when I did, the failure of a $35 buzzer might have cost me thousands of dollars in septic repairs, not to mention possibly thousands more due to backed up sewage in the house. Ewwww.

So I grabbed my Fluke TS-600 Voltage Meter (if you don’t have one, you should really get one) and investigated exactly what was happening inside my septic control box when either of my system’s alarm floats were triggered. I discovered that when it alarms, the septic control box sends 120V to two different circuits connected to the warning light and the alarm buzzer. The fact that it uses independent circuits is important; it allows you to use a switch on the outside of the box to turn off the buzzer while still keeping the warning light on if the alarm float is high.

Suddenly, just like the red warning light, a proverbial light bulb turned on in my head. What if a warning light and buzzer weren’t the only way to get notified if something went wrong with my septic system? Because the potential for damage is so high, I’d much rather get a notification that’s harder to miss… like a text message, or an email, or even a phone call when my septic alarm goes off… rather than maybe hear a $35 buzzer that had already failed once within its first 5 years of life!

The first part of a solution was to figuring out how to make a “dumb” septic control box “smarter,” so it could signal something in my house when the septic alarm sounded. The second part of the solution was figuring out how to convert that “smarter” signal into a more reliable notification method.

Making the Septic Control Box “Smart”

I tackled the first part of a solution with a Omron LY2-AC110/120 relay (less than $6 on Amazon). Often called an “ice cube” relay because it’s housed in a small clear cube, this relay would allow me to piggyback on the buzzer’s 120V circuit: whenever the buzzer sounded it would energize the relay and “close” a pair of dry contact terminals:

Omron relay, commonly referred to by geeks as "ice cube" relays.

Omron relay, commonly referred to by geeks as “ice cube” relays.

I also picked up an Omron PTF08A-E Surface Mount Socket (about $3 on Amazon) to make mounting and connecting wires to the relay super easy:

Omron relay mounting socket.

Omron relay mounting socket.

The next piece of the puzzle was a DSC WS4945 wireless door/window transmitter (less than $25 on Amazon). Because I already have a DSC alarm system with a wireless receiver at my house, as long as my septic control box is within range of my alarm system’s wireless receiver, it should be able to detect the wireless sensor’s state. I chose the DSC WS4945 because it has wiring terminals inside that are “normally closed” dry contacts which can trigger the sensor, so all I’d have to do is wire the sensor’s dry contacts to my ice cube relay’s dry contacts, and I’d be in business!

DSC WS4945 wireless alarm sensor.

DSC WS4945 wireless alarm sensor.

Here’s the inside of the sensor I bought. You can see the dry contact terminals in the lower right corner:

Dry contact terminals on a DSC W4945 sensor.

Dry contact terminals on a DSC W4945 sensor.

I used my trusty Leatherman Wave to clip and connect some low-voltage wires to the sensor’s dry contacts:

Dry contact wires attached.

Dry contact wires attached.

Then I wired the sensor’s dry contacts to to terminals #4 and #6 on the relay mounting socket (connecting to #3 and #5 would have also worked):

Relay wired to wireless sensor.

Relay wired to wireless sensor.

Time to head outside to the septic control box!

Installing the Relay and Wireless Sensor in the Septic Control Box

First, before opening the septic control box, I shut off all the breakers in the septic system sub-panel. It’s a 50-Amp subpanel with 240V circuits. That’s nothing to mess around with.

Because the alarm floats energize two separate 120V circuits (warning light and alarm buzzer), I had to choose one of those circuits to power my relay. I chose the buzzer because it could be silenced with a switch on the control box, so using that circuit would also allow that same switch to “silence” whatever other notification methods I’d set up later with my house’s alarm system. If you prefer your wireless sensor’s dry contacts to remain “open” any time the septic system is “in alarm” — even if the buzzer is silenced, then wire your relay to the warning light’s circuit instead.

Since I had to install a new buzzer anyway, started by grounding it to the metal control panel (green wire) and inserting both 120V black leads into the box:

Replacing the dead buzzer.

Replacing the dead buzzer.

Because I believe water intrusion contributed to my old buzzer’s untimely demise, I applied a generous amount of silicone to the outer edge of the buzzer, pushed it into place, then secured it from inside with the old mounting bracket:

New buzzer mounted with LOTS of silicone.

New buzzer mounted with LOTS of silicone.

Here’s the inside of my septic control box with the buzzer’s two black 120V wires not yet connected (you can see my Leatherman Wave, relay assembly, and wireless sensor sitting on top of the box near the warning light):

Buzzer leads ready to be connected.

Buzzer leads ready to be connected.

Using insulated wire-nuts, I connected the buzzer’s leads to the same wires that the old buzzer connected to, but also included a new red wire and black wire in the connections to send 120V to my relay when the buzzer sounded. I tucked the spliced connection behind the metal cover on the right side of the picture, then ran the new red and black wires over the top of the cover (there’s a plastic insulator on top so it doesn’t cut into the wires):

Red and black wires ready to power my 120V relay.

Red and black wires ready to power my 120V relay.

I mounted the relay assembly onto an open space on the panel, then connected the red and black 120V wires to terminals #7 and #8 on the relay socket. It actually worked out more cleanly for the wiring to install the relay assembly upside down and rest the wireless sensor on the bottom of the control box:

Relay assembly and wireless sensor installed in the septic control box.

Relay assembly and wireless sensor installed in the septic control box.

Here’s a close-up shot of the relay assembly mounted upside-down:

Relay assembly close-up.

Relay assembly close-up.

I turned on the breakers to power up the control box, then tested out my relay circuit. This video shows the relay closing and opening while I hit the alarm “test” switch. That’s not the relay making the buzzing sound. The buzzing you hear is the new buzzer, but since the relay is powered by the buzzer circuit, it moves in rhythm with the buzzer:

I closed up the septic control box and went back inside to “register” my new wireless sensor with my DSC alarm system and add it as Zone 29. I won’t bore you with the details (you can search online for them), but it merely entails telling your alarm system that you have a new wireless sensor and choosing what “type” of sensor it is (door, motion sensor, smoke detector, etc.). I could have programmed Zone 29 to trigger the full siren if the septic system alarm went off, but that felt like overkill. Instead, I opted for a zone definition setting that caused all the alarm keypads in the house to beep until the alarm had been acknowledged (which is zone definition 10 on a DSC system).

I walked back outside and hit the test switch on the septic panel, which caused my wife to come outside and inform me that all the alarm keypads in the house were “making a funny noise.” Success!

And…. then the phone range. It was our alarm monitoring company. They’d seen that our system had alarmed, but they didn’t recognize the zone. Oops! My wife gave them our “all clear” code word, assured them that it was just me tinkering with the system, and asked them to put us in “test mode” for an hour (which would ignore any further alarms for that period of time).

Minor inconvenience to the alarm company aside, I was elated that I’d “upgraded” my septic alarm so that if it went off, our keypads would beep and our monitoring company would call. For some, that might be upgrade enough! But I wanted to take it to the “next level.”

Enabling “Smarter” Notifications

I already consider having the septic alarm cause my alarm keypads to beep until they’re acknowledged (and the potential for a phone call from a live human) a major upgrade to the simple light and buzzer notification system. But as it turns out, taking notifications to the “next level” was easy. So easy, in fact, that I didn’t have to do anything… because I’d already done it. Let me explain.

Years ago, I added an Envisalink (an $80 device made by EyezOn) to my DSC alarm system. I actually blogged about it in March 2011. Basically, it’s an add-on board that makes a “dumb” alarm system “smarter” by connecting it to the Internet, thereby enabling web and mobile app-based control of your alarm system. The Envisalink also enables automatic email and text notifications whenever an alarm zone is triggered, and I’d had that functionality configured and working for years.

So what I didn’t tell you about the first time I tested my new relay/wireless alarm sensor setup above (when my wife came outside and the alarm company called) is that I also received an email and a text from my Envisalink as soon as I sounded the buzzer, telling me that “Zone 29” was in alarm. Then I received another email and text telling me the zone had “restored” when I let go of the test switch.

But “Zone 29” is more than just a number to me, so to pretty things up, I logged into my Envisalink account and renamed Zone 29 as “Septic Alarm.” Now my Zone 29 alarm and restore texts look like this:

This is the text I get when the septic alarm is tripped.

This is the text I get when the septic alarm is tripped.

This is the text I get when the septic alarm is restored.

This is the text I get when the septic alarm is restored.

Now I have exactly the notifications I want. I’ve told my alarm monitoring company to ignore any alarms on Zone 29, because I’d like to be able to periodically hit the test switch to verify that the light, buzzer, and smart notifications are working.

Other Ideas for Triggering Notifications

Of course, this isn’t the only way to make your septic system “smarter” and increase the chances of you learning about possible septic problems before they get too serious. These same concepts can be applied to a number of technologies. For example, if you have a SmartThings hub (I have one and love it), you could use the same Omron relay wired to the 120V circuit of the septic light or buzzer, but instead of wiring the dry contacts to a DSC wireless alarm sensor like I did, you could wire it to any number of Z-Wave dry contacts which would make your SmartThings hub aware of the alarm — then configure any number of notification methods from the SmartThings hub (including email or text). Some SmartThings users have even gone so far as to track their septic system’s pump usage, as discussed in this thread.

Another thing I’ve considered is running parallel notification methods from my relay. That Omron relay closes terminals #4 and #6 when energized, but it also independently closes #3 and #5… meaning I could trigger a separate dry contact from those terminals. Just for fun, I might try a Z-Wave dry contact to my SmartThings hub, just to see what else I can do with it.

Of course, technology advances quickly, and I have no doubt that as smart home technologies (like the ones we discuss over on SmartHomeHub.net) expand, my $34 home-grown solution for smarter septic tank monitoring will eventually be a dinosaur.

But for now, I sleep better at night knowing that even if I can’t see the warning light or hear the buzzer on my septic system control box, I’ll still hear about it from my alarm keypads, phone, and inbox… and I’m less likely to end up with a smelly basement and a lighter wallet.

List of Components

If you’d like to re-create this project exactly as I did it, here’s what you’ll need:

  • Omron LY2-AC110/120 relay (less than $6) to allow a 120V circuit to trigger a dry contact.
  • Omron PTF08A-E Surface Mount Socket (about $3) to make mounting and connecting to the relay easy.
  • DSC WS4945 (less than $25) to trigger an “open zone” alert to a DSC alarm system.
  • Envisalink (around $80) add-on board for DSC alarm systems to allow remote status monitoring and notification of alarms.
  • A little bit of wire and some wire nuts to make the connections.

As always, I welcome your questions, comments, and feedback — especially if you have a different solution for solving this same problem!

  • ReD-BaRoN

    Love your posts, Steve (minus the gun ones, not a gun guy). Advanced DIY guy after my own heart. Always looking to learn why things work the way they do and how to make them better. Wish I knew how you find the time.

    • Thanks, Baron. I can appreciate you not being a gun guy – not everyone is, and that’s OK. 🙂 But glad you still come read the DIY stuff!

  • Thanks, car_kel! 🙂

  • Thanks! But it really is as simple as buying the same two items (relay and wireless sensor) and hooking it up! If you’ve got a local geeky friend, I bet they could do it for you! 🙂

  • Thomas Burkholder

    Hi Steve. Thanks for this – I’m building a house here in Vancouver BC, and I’m just trying to get my DSC panel/envisalink EVL-4 arrangement set up. Actually that’s all working, but I’m contemplating now how to hook up my sump alarms (storm and sanitary pump control panels) to the DSC box and then receive text messages via the envisalink box. Sort of important for me as the basement will flood within a few hours in the winter time if the storm sump fails. Anyway, all this gear is in the same mechanical room, and for reliability, I’d like to avoid the wireless trick you used and go all-wired. I’m a software engineer but just so-so on electronics. Any idea what kind of relay I’d use to generate a signal for a zone in the DSC panel from a 120v signal in the sump alarm float? It’s pretty clear from the wires I don’t want to send 120v to the DSC :-). Once that’s done, is there some special way to program the zone (maybe a zone type?) in the DSC panel so that it generates an alarm even when the system itself is not armed (you obviously want to generate an alarm if the alarm float is up, even if the alarm system is not armed). Anyway, if you can point me in the right direction I’d be grateful. Thanks again for the great post here.

    • Hi, Thomas! You can do exactly what I did with the exact same relay, which takes a 120v input and then just closes a dry contact, but use a wired door sensor instead of a wireless one. Then simply hardwire the door sensor into your panel as a normal zone. And yes, there is a zone type you can set so that it alarms even if the alarm isn’t set. I think there’s a “water” zone type available, but I don’t remember the number to program off hand. I’ll bet its on your worksheets (I always search and download new ones when I forget that stuff). Good luck – lemme know how it goes!

      • Thomas Burkholder

        Hm, not sure I fully get it – sorry, like I said, not a hardware guy by default. I think I get the relay now – it just connects the dry contact terminals together when 120v is applied to the other side, right? Now that I think about it (and RTFM), would I even need a door sensor on the dry terminals? Why not just use the dry contacts to connect a wire from COM to whatever zone I’m using? Thanks again

  • G Venkataraman

    Hi Steve,
    New owner of a house with septic here in Woodinville, WA, also uninc. King County – north of Lake Washington. Septic alarm went off before I moved in! I left the water running in one bathroom by mistake. I will be setting up an ADT-DSC system in a few days. They do not do the septic alarm hookup. Any update to your post or advice for me? Thanks.

    • No update! This setup is still working great for me! 🙂

  • Mike c

    Hi Steve. Great post. Stupid question: if the septic control panel itself fails, how will you know? Do any of the newer control panels come with some redundancy to protect against failure of the panel itself? I ask this because I have a vacation condo, and the complex is basically empty for the entire winter and only partially filled in the summer. This summer our pump failed. The red light was on in the basement for weeks and no one had any idea what it meant. We plan to connect our control panel to our security alarm company panel. But the question was raised, what if the panel itself dies? How would we know short of sewage backing up? Thanks.

    • If the panel fails, you’re in trouble. That’s why it’s a good idea to test your panel (by manually hitting the switch) every 6 months.