Nitrite Reducing Bacteria Test Tubes (10 Pack)

£220.00 ex. VAT

Our NRB boxes are available in multiples of 5

Our bulk order volumes allow us to provide exceptional value for money on Tube Tests.

Each box contains 10 Tubes (5 boxes equals 50 Tubes per order)


Nitrite Reducing Bacteria Tube Test

Accepta’s high quality NRB tube tests offer a quick and easy means of monitoring nitrite reducing bacteria present within water systems treated by Nitrite, making them ideal for engineers, water treatment professionals; and building services and facilities management specialists.

Accepta’s NRB tubes and dipslides are manufactured to the highest quality standards and are used to measure the levels of NRB found in treated water systems.

If you are looking for incubators you can find them here

Incubation Chambers

Accepta’s Nitrite reducing Bacteria (NRB) Tube Test is design to assess the contamination of water samples with nitrite reducing bacteria.

The test contains a pale orange medium which reacts to metabolism by NRBs to produce a semi-quantative result within 5 days.

The NRB Tube Test is used to monitor the levels of NRB in water systems, with specific relevance to systems which use nitrite as their main corrosion inhibitor. NRB’s are able to metabolise nitrite into ammonia and nitrogen gas which are aggressive corrosive agentss, as well as this the corrosion inhibition of the nitrite is lost.


Pipette 2ml of the sample into the tube and immedtiatly replace the cap placing upright in an incubator.

For testing corrosion pits swab them with a sterile swab, pierce the gel with a swab and place into the incubator. Contamination is defined by blackening around the swab.


Incubate at 35C for up to 5 days, check daily to determine the level of contamination.


Used tests should be incinerated or autoclaved. Alternatively, open and immerse in a 10% bleach solution for 24 hours.

Classification of Results

Results are to be determined by the colour change seen on day 1 through to 5. No colour change or bubble formation can be interpreted as no contamination. A partial colour change (top of the medium is red, bottom still pale orange) and moderate bubble formation suggests a moderate contamination. Where a full colour change is seen accompanied by ample bubble formation, heavy NRB formation is assured. Strong acidic or alkaline samples can cause an instant colour change, in this event contamination can be determined by bubble formation alone.

Please Note. If the colour change is immediate on adding the water to the tube, this is due to the pH of the water. Colour changes that occur only after incubation but without bubbling (gas production) should be considered as a low level positive. Samples with both colour change after incubation and gas production are read as the chart within the kit.

Interpretation of Results

As noted the recommended incubation time for this test is up to 5 days. Indication of the level of contamination can best be obtained by daily checking of the incubated tubes. On a daily basis assess the percent (%) Colour Change & Bubble formation in each incubated tube. Record the percent change and the associated number of days incubated. The degree of contamination is assessed by how much change has occured and the rate at which it occurred (the number of days).

System Treatment

IMPORTANT – Monitoring is not a substitute for a treatment regime, you should seek the advice of a professional water treatment or environmental company who will supply a risk assessment together with the required treatment system. Speak to us for advice on chemical treatment and maintaining control in your system.

Other Incubated Media

Application Media Side 1 Media Side 2 Detection of
Cooling water & cutting fluids Nutrient & TTC Malt Ext. TVC, Yeast & Moulds
Standard total counts in cooling water Nutrient & TTC Nutrient & TTC TVC (also TTC2 trade+)
Food & personal hygiene Nutrient & TTC MacConkey No.3 TVC Coliforms
Food industry – high protein samples Nutrient & TTC Rose Bengal TVC Yeast & Moulds
Multiple applications Nutrient & TTC Chromogenic TVC, Coliforms & E.coli

Note – All Accepta dipslides can be own labelled, please contact us for further details.

Note on loss by NRB vs Nitrification

The test for NRB (Nitrite Reducing Bacteria) is based upon the detection of ammonia formed by the reduction of NO2 and subsequent biochemical pathway to form ammonia (NH3). This is nitrite reduction. There are some bacteria that will convert NO2 to form N03 or nitrates. These are known as nitrifying bacteria. This pathway can be problematic but is generally limited by how much oxygen is in the system, where oxygen availability is the limiting factor.

Nitrifying bacteria do not produce ammonia and therefore are not detected by the NRB test and there are no specific and good tests for nitrifying bacteria. However, monitoring the aerobic colony count over a period of time gives a good indication of overall microbial load in the system. This can be taken to include the nitrifying bacteria.

Technical Support

If you require additional information or specialist technical support concerning our dipslides please contact Accepta’s technical support team.

Additional information

Weight 2 kg