Water bath
A tank of water held at a constant set temperature, used to warm, incubate or melt samples gently and evenly.
- Pharmaceutical
- Microbiology
- Food & dairy
- Clinical laboratories
- Research
Test your Water bath knowledge
Multiple-choice questions
Pick an answer to see whether you are right and why.
Q1. What water should be used to fill a laboratory water bath?
basicQ2. Five positions read 36.8, 37.1, 36.9, 37.3 and 37.0 °C. What is the uniformity?
basicQ3. Using the same readings (set point 37.0 °C), what is the accuracy?
intermediateQ4. Melted agar is commonly held in a water bath at about:
basicQ5. Why do many water baths have a gabled (sloping) lid?
intermediate
Viva questions
Think of your answer first, then open it to compare.
1. How do you calibrate a water bath?
Stabilise the bath at the set point, measure the water temperature with a calibrated reference thermometer at several positions (e.g. four corners and centre), and compare the mean with the set point (accuracy) and the highest minus lowest reading (uniformity) against SOP limits.
2. What problems arise if the water is not changed regularly?
Algae and bacteria grow, which can contaminate samples (especially in microbiology), and scale builds up on the heater and sensor, harming heating and control.
Keep every Water bath in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.