Market Debut of Portable Water Quality Measuring System (U-50 Series)

26. August 2008

  • Capable of measuring 11 parameters
  • Equipped with an EPA-compliant*1 high-sensitivity turbidity sensor, for detecting even slight changes in the turbidity of environmental waters
  • Low operating cost, affordable for developing countries to improve their water environments

HORIBA has developed a portable water quality measuring system “Multi Water Quality Checker” U-50 series (five models) that is capable of real-time, on-site measuring of up to 11 water-quality parameters (pH, dissolved oxygen, etc.) in environmental waters such as rivers and lakes. Equipped with a high-performance turbidity sensor with tenfold sensitivity, higher than that of the conventional counterpart, the U-50 series system can measure even the slightest turbidity in water as clear as tap water. The U-50 series is thus applicable to various measurement purposes such as measuring natural environmental water quality (main use of the conventional counterpart) and testing water supplies*2.
[This system has adopted the measurement principle specified by the Environmental Protection Agency (EPA).]

The U-50 series system uses ancillary components having a long service life between replacements to ensure high maintainability. Moreover, it is designed to be waterproof for the highest robustness. The U-50 series therefore enables any person to measure water quality easily, accurately and at low cost even under adverse conditions where measurement is difficult. The system will be put on the market on October 1 of this year through major HORIBA group companies, mainly targeting overseas markets, including developing countries that cannot afford installation of numerous large measuring systems, and large countries such as the U.S. that require water-quality monitoring at many fixed points using portable instruments.

Significance of water-quality measurement

In 1970, Japan enacted the Water Pollution Control Law as an environmental pollution preventive measure. Similar water environment regulations*3 have also been enforced in the U.S. and European countries. Against this background, water quality is measured at various sites, including seas, rivers, groundwater, industrial wastewater, and effluent from garbage incineration plants, for protection and improvement of the water environment. The recent global water resource shortage urges each country to secure its own safe water resources and, for this reason, to measure the water quality of its various water resources, such as rivers, lakes and groundwater.

Features of the new U-50 series products

Like its conventional counterpart, the new U-50 series system is a portable water quality measuring instrument comprising a sensor probe and main unit with measurement and display functions. Features of the new series system include:

  • Both the sensor probe and main unit offer robust construction, enabling measurements under adverse conditions.
  • Up to 11 water quality parameters can be measured simultaneously on-site using a single system (U-53/53G).
  • The system's turbidity sensor (U-53/53G) is equipped with a wiper and high-intensity tungsten lamp as the light source that provides tenfold sensitivity, higher than that of the conventional counterpart. This enables accurate turbidity measurements even in clear water where bubbles could cause measurement errors. Because of this feature, the U-53/53G system can be used to test the turbidity of drinking water, in addition to monitoring and controlling environmental water quality, which is the main function of the conventional counterpart.
  • Due to the long-life sensor probe and reference solution elaborately prepared for simultaneous calibration for five ingredients of water, the U-50 series system is easy to maintain and manipulate, promising long-term reliable measurements even in remote locations far away from towns, i.e., the system is suitable for use anywhere in the world as a global environmental monitoring instrument.

Because of these functions and features, the U-50 series water quality measuring system is expected to be adopted in a wide variety of sectors, from professional research institutes and developing countries to nonprofit organizations and general citizens, for contributing to the protection of the global water environment.

Measurement items

  1. Hydrogen-ion concentration (pH): An indicator of a liquid's property. The U-50 series system indicates this property in terms of acid, alkali or neutral.
  2. Dissolved oxygen (DO): The concentration of oxygen dissolved in a liquid, an indicator of eutrophication
  3. Conductivity (COND): Total ion concentration, an indicator of contamination level
  4. Turbidity (TURB): An indicator of the amount of contaminants or water turbidity [Not applicable to Model U-51]
    Note: Model U-53/53G contains a tungsten lamp as the light source to ensure high-precision turbidity measurements.
  5. Oxidation/reduction potential (ORP): An indicator of oxidation tendency (or reduction power)
  6. Salinity
  7. Specific gravity of seawater
  8. Total dissolved solids (TDS)
  9. Water temperature
  10. Water depth [Not applicable to Model U-51]
  11. GPS (Location measurement by the built-in global positioning system): [Applicable only to Model G-53G/52G]

Details for each model



pH, dissolved oxygen, conductivity, ORP, salinity, specific gravity of seawater, TDS, and water temperature


Same measurement items as for Model U-51, plus turbidity (Light source: LED)


Same as above, plus water depth and GPS


Same measurement items as for Model U-51, plus turbidity (Light source: tungsten lamp for high-precision measurement) and water depth


Same as above, plus GPS



Major specifications

Measurement items [System with 2 m cable]


Sensor probe

External dimensions: 96 mm × 340 mm,
Waterproofed (JIS protection grade 8),
Mass: Approx. 1,800 g

Main unit

External dimensions: 115 (W) × 65 (D) × 280 (H) mm,
Waterproofed (JIS protection grade 7),
Mass: Approx. 800 g




*1: EPA-specified measurement principle

The Environmental Protection Agency (EPA) is the U.S. administrative agency in charge of managing atmospheric, soil and water pollution. The EPA specifies that groundwater turbidity measurements should use a high-intensity tungsten lamp positioned so that the angle between transmitted and scattered light beams is 90 degrees.

*2: Water supply testing

Refers to the testing of drinking water quality, conducted periodically and as necessary. In Japan and many foreign countries, it is required by respective appropriate administrative organizations to measure the pH, conductivity, ORP, temperature and turbidity of tap water and groundwater for drinking use.

*3: Water environment regulations

The U.S. government has not established such an area-wide total water pollutant load control system as in Japan. Instead, individual states specify their own measurement items for water-supply testing of groundwater and reservoirs for drinking water.