HL7 water quality sonde placed in a flowing stream.

HYDROLAB – Water Quality Monitoring

Data you can trust. Diverse sensor options.

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History of HYDROLAB

A hydrologist spot sampling with a HL7 sonde and reading data with a surveyor in a body of water.

HYDROLAB water quality instruments and software help environmental scientists and managers monitor important changes in watersheds by providing continuous, trusted water quality data.

Since we introduced the industry’s first multiparameter water quality probe for field use in 1968, we have consistently produced high-performing instruments and software solutions designed for real-world functionality.

Today, HYDROLAB products are created for accuracy, usability, and ease of use. Our sensor designs provide long-term, continuous monitoring, portable, flexible spot monitoring, and short-term study support.

HYDROLAB sondes are known for sensor diagnostics and comprehensive metadata information to provide traceability on valuable data. Users can reduce the risk of errors with calibration history and safeguard field measurements with smarter verification methods.

Easy-to-use software tools support decision making, minimize errors, and increase efficiency by streamlining data collection and calibration tasks in the lab or at deployment locations. HYDROLAB is part of OTT HydroMet, a subsidiary of Veralto Corporation, and is now one of the strong global product brands that make up OTT HydroMet.

Featured Products / Product Families

Learn how we support monitoring programs through proven sensor technology, versatile and durable sonde design, and intuitive software.

HYDROLAB HL4 and HL7 sondes for water quality monitoring.


Our HL7 and HL4 sondes include intuitive software for unmatched usability, exceptional power performance and diverse sensor options, all delivering high data quality and reliability.

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Two internal sensors for specific parameter measurement for use with HYDROLAB sondes.


Proven sensor technology.

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Close up of the depth sensor for use with HYDROLAB sondes.

HYDROLAB Depth Sensors

Depth measures absolute hydrostatic pressure from an internal diaphragm. Sensors are optimized for depths down to 25 m, 100 m, or 200 m.

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HYDROLAB Operating Software

HYDROLAB Operating Software user interface

This powerful software tool helps to make better decisions, minimize errors, and increases efficiency in the lab and on the deployment site.

  • Quickly view the current status of the instrument and ensure its working properly

  • Maximize uptime with streamlined calibration tasks

  • Plot current and historic data with multiple graphics and table formats options

HYDROLAB Applications

Discover the ways we are supporting surface and groundwater monitoring through reliable data. We offer water quality monitoring instruments for: lake and reservoir profiling, river and stream surveys, coastal monitoring, groundwater studies, wetland management, harbor and port investigations, aquaculture protection and much more.

Multiple staff gauges to provide  water level measurements for a reservoir.

Water Level 

We offer multiparameter sondes for the measurement of water quality either in spot sampling or unattended continuous deployment.

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A hydrologic technician spot checking water quality in a stream with a HYDROLAB HL4 and surveyor.

Water Quality

From long-term unattended monitoring to spot sampling, HYDROLAB multiparameter sondes offer rugged and flexible options for water quality measurement. Choose from compact options for easy spot sampling and groundwater measurement or a more robust sonde with diverse sensor and anti-fouling options.

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A Harmful Algal Bloom (HAB) in a river with a city in the background.

Nutrient Monitoring

HYDROLAB multiparameter sondes have several sensor options for nutrient measurement as well.

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Featured Projects

Read how our instruments are making a difference in the world through customer success stories.

Two scientists monitoring water quality in a half frozen body of water.

Water Quality Monitoring on the Mississippi River

In this project, water quality data collected by the HYDROLAB DS5X and Hach Nitratax sensors played a key role in the study of freshwater mussels and the nitrogen cycle. The sensors measured highly time sensitive data in large scale systems despite harsh aquatic conditions.

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A group of researchers monitoring nitrate in an agricultural setting.

HYDROLAB University of Iowa

Nitrate-loading data are essential for assessing amounts of nitrate entering streams from farm fields. A research institute at the University of Iowa uses this data to track statewide water quality conditions in real-time to populate models to evaluate water quality and volume, while enabling end user analyses to identify nitrate-rich water sources.

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OTT HydroMet Blog

Observing the elements is key to better understanding our planet. This blog tells the manifold stories of experts working in environmental monitoring with help of our sensors and solutions.

The city of Charlotte, North Carolina with clouds in the sky.

See How Mecklenburg County Monitors Water Quality

Learn how the team at CMSWS, the North Carolina Department of Transportation (NCDOT), and OTT HydroMet came together to implement an extensive watershed-level monitoring program.

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Lab testing of water quality grab samples.

Turbidity Measurement: Why Does it Matter?

Turbidity is one of the most talked about parameters in environmental water quality monitoring, yet the details around turbidity measurement are not always known or fully understood. Use our guide below for a better understand of all thing’s turbidity!

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A green wave of water with high concentrations of algae washing up on a beach.

Trends in Nutrient Monitoring

The nitrogen and phosphorus pollution of water has the potential to become a significant environmental problem. Our recent whitepaper deals with this topic and discusses possible solutions.

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Have Questions? We Have Answers!