Published 2 July 2026 at 18:29
Looking at water is a poor measurement method. A sample from a stream that “looks clear” can contain 5 NTU. A sample from tap drinking water that “looks slightly cloudy” can contain 0.3 NTU. The difference is significant — 5 NTU exceeds the Swedish guideline value for drinking water according to SLVFS 2001:30, while 0.3 NTU is well within specification. The eye is simply not calibrated to measure small turbidity deviations, but it is precisely these small deviations that determine whether a water system is functioning correctly. For this, an instrument that measures turbidity objectively is required.
What NTU is and why it is the standard unit
NTU stands for Nephelometric Turbidity Unit — a measurement based on how much light is scattered at a 90° angle by particles suspended in the water. A small amount of inorganic particles (silt, clay, sand) or organic material (bacteria, humus, algae clusters) changes how the water scatters light. NTU is a standardized, comparable unit that allows a measurement taken here to be compared with a measurement taken elsewhere, at another time.
The portable turbidimeter TB400 measures up to 1,000 NTU with a resolution of 0.01 NTU. This covers everything from crystal-clear drinking water (typically 0.1–0.5 NTU) through natural seawater samples (2–10 NTU) and rainwater runoff (50–200 NTU) up to very turbid process streams (500–1,000 NTU).
Why portability matters
Traditional turbidity measurements are laboratory work. A water sample is bottled, transported, waits in the queue, is measured, and the result is delivered days later. During that time, everything has changed: the measurement situation that gave problem signals is over, or — worse — the problem has spread while waiting for the answer. Portable measurement breaks this delay.
The TB400 measures with a 10 ml sample volume, takes less than 30 seconds from sampling to reading, and is built with a splash-proof front panel for field use. Two-point calibration is performed against the included 0 and 100 NTU standard solutions, and once calibrated, the instrument remains accurate for months.
Where the meter is used in practice
Municipal and private water treatment: Turbidity is the single best indicator that a filter bank system is functioning. Rising turbidity after the sand filter reveals a filter breakthrough before bacteria reach consumers. Continuous portable measurement complements continuous inline monitoring by enabling tracking measurements when deviations occur.
Food and beverage industry: Control of process water, rinse water, and final washes. Declining water quality during batch production is revealed here — and can be addressed before the entire batch is contaminated.
Breweries: Beer clarity is both a quality indicator and a process parameter (filtration, clarification). Portable turbidity measurement during fermentation provides direct feedback on the state of the process.
Environmental monitoring: Monitoring of waterways after storms, measuring downstream from construction sites, checking stormwater from industrial areas. Deviating turbidity is often the first sign that something has happened.
Aquaculture and fish farming: Water quality is a decisive factor for the health of fish and shellfish. Continuous portable measurement complements fixed parameters to verify the function of water treatment systems.
Swimming pools and spa facilities: Control of pool water clarity according to the recommendations of the Public Health Agency of Sweden. Rising turbidity indicates that the load exceeds the capacity of the treatment system.
Emergency water works and disaster response: In case of disruptions to the regular water supply (e.g., after flooding or pipe bursts), water quality must be verified on-site before it can be distributed to consumers. Portable measurement makes this possible.
What you get for your money
0.01 NTU resolution in the range 0–1,000 NTU, ±2% accuracy, 10 ml sample volume, two-point calibration, battery-powered for field use (6 × AAA), Data Hold, Min/Max recording. Delivered with 0 NTU and 100 NTU standard solutions for calibration, cleaning solution, test bottles, cleaning cloth, and a hard carrying case for transport.
10,718 SEK is a one-time cost that a water utility operator or food manufacturer recoups with a single avoided problem — where on-site measurement identified an issue within minutes instead of days. For institutions responsible for public health-critical water systems, portable turbidity measurement is not a luxury investment — it is standard equipment in the readiness setup.
Read more: Portable turbidimeter TB400 in the shop →
