Septic System Answer Man - January 2022

With rising vacation rentals and general lack of onsite wastewater, data loggers can quickly show spikes in water usage or patterns of misuse in septic systems.

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About 35 years ago a colleague and I were working on a research/demonstration system consisting of a septic tank, pump tank and a series of trenches fed by dropboxes. A common system now, but at the time innovative. Each trench was fitted with inspection ports to monitor water levels in each trench when we periodically visited the site. Inside the house we installed a water meter to keep track of the amount of water used. The system was designed for a typical 3-bedroom house and an estimated sewage flow of 450 gpd.

After a few months we noticed something unexpected. There was water/sewage present in all the system trenches. We were also seeing water meter and pump cycle counter readings indicating a lot more water usage in the house, about 2.5-3 times our estimated daily use projection. The system was being hydraulically overloaded. Among other recommendations this led us to suggest/recommend that all onsite systems should have water meters. This idea was not that well received at the time. Few permitting authorities required them, and few installers put them on their systems. 

There have been a lot of advances in the industry in terms of pump controls, measuring water levels in tanks, measuring daily flows and water use events and effluent quality. They provide the installer, service provider and homeowner an opportunity to monitor system operation and performance in real time. This is done through incorporation of data loggers into control panels.


A data logger or a data recorder is an electronic device that continuously records data over time either using a built-in instrument or connected to external sensors. They use digital processors and usually look like a small box with batteries, wires, an internal memory storage, sensors and a programmable module. Data can be shown with a personal computer, LCD screen or a mobile phone.

Advantages to data loggers are they automatically collect real time data from the sensors — in our case usually flow events and water levels. But if connected to various sensors, they can record turbidity 

(suspended solids), total phosphorus or other water quality parameters. This can be displayed on the computer or mobile device such as a phone or tablet. Data loggers can be left unattended and accessed remotely (from the office or home).

Data loggers are available to record a single channel or parameter; if you are only interested in flow a single channel would work. If you want to keep track of more parameters than one, multiple configurations are necessary. Work with your supplier to determine the best configuration and product for the parameters you want to record.

The length of time a data logger can operate depends on the power backup and the built-in memory capacity. While most are durable and can last for a long time, again the type and size will be determined based on what you need to capture, store and retrieve as a continuous record, at predetermined time intervals or when flow occurs.


In general, limiting the number of readings per day will preserve battery life if it is located away from a power source. Similarly, the amount of memory needed will depend on what is being measured and the frequency on measurement. This should be considered carefully when choosing the data logger. Be aware some operate to overwrite data once the memory is filled, while others will just stop recording data. 

If you want to be notified if, say, the water level reaches a certain level in the tank or operating sewage trench, data loggers can be set to deliver a text message or email to your phone or other devices. In addition, they can come equipped with a light or alarm buzzer to warn the homeowner.

There are several options available to retrieve data. It can be downloaded directly to a PC or tablet, transferred to a USB drive, or automatically transmitted remotely to a PC at a central location. Data is uploaded and saved to the cloud for access by different devices using a login and password.

Data loggers are configured to save the data in a database so it can be retrieved and displayed in table or graphical formats as desired. For presentation to the homeowner, graphical formats are often the most effective way to present the information when discussing system performance.

Many of you are already using data loggers in your business. For those who have not, consider the example I used at the beginning. Think about a situation you may encounter where recognizing a system at risk of hydraulic overload in real time can prevent long-lasting system damage. Or consider a situation where a sewage backup is about to occur and can be addressed before it happens, helping your client avoid loss. Further, through the data display you can show clients why the action you are suggesting is necessary. It will make your job much easier and result in a satisfied customer.


A current example from a recent reader highlighted they use data loggers for Airbnb or Vrbo houses they service. People who rent these houses have a tendency to use a lot more water than a regular family. This means systems serving these types of houses may have to be enlarged and require more regular maintenance work. Monitoring system use is a critical piece for owners and renters to avoid system problems. This reduces landlord headaches and provides for happy renters.

One last thought: As regulatory authorities require more monitoring to assure system compliance, you and your business will likely find an increasing need to collect, store, display and provide system data. 


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