B.O.D Bottles

Quick Answer: B.O.D Bottles are glass bottles used in the biochemical oxygen demand (BOD) test, which measures how much dissolved oxygen microbes use while breaking down organic matter in water. BOD bottles have a stopper shaped to shut out air, so the oxygen in the sample can be measured before and after incubation.

How BOD Bottles Are Used

In a BOD test, a water sample, diluted if necessary with aerated dilution water, is filled into two or more bottles right to the top so that no air bubble is trapped. The stopper, which is usually tapered to a point, pushes out excess liquid as it is inserted. Dissolved oxygen is measured in one bottle straight away and in another after incubation in the dark, commonly for five days at 20 °C. The difference, corrected for dilution, is the BOD, a standard indicator of organic pollution in rivers, lakes and sewage.

The flared lip around the neck holds a little water above the stopper, a water seal that stops air entering during incubation; some bottles also take a plastic cap over it. Oxygen is read either by Winkler titration, which fixes the oxygen as a precipitate inside the same bottle, or with a dissolved oxygen meter using a probe made to fit the neck.

Biology students also use these bottles for the light and dark bottle method. Pond water is sealed in a clear bottle and a blackened one and suspended in the pond: oxygen falls in the dark bottle through respiration only, and changes in the light bottle through photosynthesis and respiration together, so gross and net primary productivity can be calculated. A 300 ml BOD bottle is listed separately; the capacity of these bottles is not stated.

Applications

• BOD testing of river, lake, well and wastewater samples in environmental science labs
• Monitoring treatment plant performance in college and municipal practicals
• Light and dark bottle measurement of primary productivity in ecology fieldwork
• Winkler dissolved oxygen practicals in chemistry and biology classes

Cleaning and Handling

• Keep each stopper with its own bottle, because a ground stopper may not seal well in another bottle; number both with a marker that survives washing.
• Clean the bottles thoroughly and rinse them well; traces of detergent or organic matter use up oxygen and raise results.
• Store bottles with a strip of paper between stopper and neck so they do not seize.
• Handle filled bottles by the body, not the stopper, when moving them to and from the incubator.

Specifications

Why Choose LabEquip

Environmental science departments, public health labs and ecology teachers buy these bottles in sets, because every sample needs at least two. LabEquip lists them in Biology Lab Products; send the quantity and capacity you require through the contact page.

Frequently Asked Questions

Why do BOD bottles have a pointed stopper?

The tapered tip pushes excess sample out as it is inserted, so no air bubble is trapped under the stopper. Any trapped air would add oxygen and spoil the measurement.

What is the flared lip for?

It holds a small amount of water above the stopper as a water seal, which stops air from entering the bottle during incubation.

How long are samples incubated in a BOD test?

The common standard is five days in the dark at 20 °C, reported as BOD5. The dark prevents algae in the sample from producing oxygen by photosynthesis.

What is the light and dark bottle method?

Water from a pond or lake is sealed in a clear bottle and a darkened bottle and incubated in the water body. Oxygen change in the dark bottle shows respiration, and in the light bottle the net result of photosynthesis and respiration, giving primary productivity.

How should the bottles be cleaned?

Wash with laboratory detergent, rinse thoroughly with tap water and then with distilled water. Any residue of detergent or organic matter consumes oxygen and gives falsely high BOD readings.

What capacity are these bottles?

BOD bottles are commonly made in 300 mL, the volume used in many standard methods, but other sizes exist and this listing does not state the capacity, so confirm it when you enquire.

Last Updated: September 2026