WATER TYPES AND APPLICATIONS

Picking the type of water quality you need

Selecting the water quality you need is an important step to when purchasing or operating a high purity water system. It can be very expensive to add additional purification technologies after you purchase a system. For this reason you should choose your type of water based on the application you have that requires the highest purity of water. Most scientific application follow the recommendations of the NCCLS or the C.A.P. committees. These member based committees set water purity specifications after reviewing current applications and carefully consulting the scientific communities.

Water Quality Standards
NCCLS/CAP Reagent Grade Water Types & Specifications
A.T.S.M.
A.A.M.I. Hemodialysis
Semi-Conductor Water Quality
NATIONAL PRIMARY DRINKING WATER REGULATIONS
USP 23 Pharmaceutical Grade Water

Most common in laboratories

NCCLS/CAP Reagent Grade Water Applications

Type I:
This type is used for applications requiring minimal interference and maximum precision and accuracy.  These include atomic absorption, flame emission spectrometry, ligand assays,  trace metal analysis, enzymatic procedures sensitive to trace metals, electrophoresis, high sensitivity chromatographic procedures, buffer solutions, flurometric procedures and standards solutions.

Type II:
Water of this type is used for applications where presence of bacteria in purified water can be tolerated. These include general reagents without preservatives, microbiology systems (not to be sterilized). Also test methods for which requirements leading to the choice of Type I or Special Purpose waters do not apply; stains and dyes for histology, general reagents with preservatives and microbiology systems (to be sterilized).

Type III
This grade water is used for general washing and as feed water for producing higher grade water, as well as some non-critical bacteriological media preparation.

Special Purpose Water
Includes procedures requiring removal of additional contaminants:  This may include the removal of pyrogens for tissue/cells cultures, removal of trace organics for HPLC or specialized water for use with in vitro fertilization applications. 

NCCLS/CAP Reagent Grade Water Specifications (maximum levels)

Resistivity

Silicate (SiO₂)

Bacteria

In addition the NCCLS specification requires filtration through activated carbon, distillation or reverse osmosis to reduce the total organic carbon levels in the water.