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Type III — RO grade
Type III RO Water Systems
Type III laboratory water systems produce reverse osmosis grade water meeting ASTM D1193 Type III limits: 4.0 megohm-centimetre minimum resistivity, conductivity at 0.25 microsiemens per centimetre maximum and TOC at 200 micrograms per litre. They serve glasswash, autoclave feed and reagent make-up.
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Answer first
What Type III RO Water Systems Are, and How They Are Specified
Type III laboratory water systems produce reverse osmosis grade water meeting ASTM D1193 Type III limits: 4.0 megohm-centimetre minimum resistivity, conductivity at 0.25 microsiemens per centimetre maximum and TOC at 200 micrograms per litre. They serve glasswash, autoclave feed and reagent make-up.
Type III is where most laboratory water volume is actually consumed. Glassware washing, autoclave feed, water baths and general rinsing use far more litres than analytical work does, and using Type I for them is expensive without being better.
It is also the base stage of most laboratory water systems. An RO module produces Type III, and the higher grades are produced from it by adding deionisation, UV and filtration stages.
Specification
ASTM D1193 Type III limits and typical configuration
| Parameter | Type III limit | Notes |
|---|---|---|
| Resistivity, min | 4.0 MΩ·cm at 25 °C | Higher than the Type II minimum of 1.0 |
| Conductivity, max | 0.25 µS/cm at 25 °C | Tighter than Type II at 1.0 µS/cm |
| TOC, max | 200 µg/L | Looser than Type II at 50 µg/L |
| Sodium, max | 10 µg/L | Looser than Type II at 5 µg/L |
| Chloride, max | 10 µg/L | Looser than Type II at 5 µg/L |
| Total silica, max | 500 µg/L | Considerably looser than Type II at 3 µg/L |
| Typical production route | Reverse osmosis, or RO followed by DI | The base stage of most laboratory systems |
Resistivity, min
- Type III limit
- 4.0 MΩ·cm at 25 °C
- Notes
- Higher than the Type II minimum of 1.0
Conductivity, max
- Type III limit
- 0.25 µS/cm at 25 °C
- Notes
- Tighter than Type II at 1.0 µS/cm
TOC, max
- Type III limit
- 200 µg/L
- Notes
- Looser than Type II at 50 µg/L
Sodium, max
- Type III limit
- 10 µg/L
- Notes
- Looser than Type II at 5 µg/L
Chloride, max
- Type III limit
- 10 µg/L
- Notes
- Looser than Type II at 5 µg/L
Total silica, max
- Type III limit
- 500 µg/L
- Notes
- Considerably looser than Type II at 3 µg/L
Typical production route
- Type III limit
- Reverse osmosis, or RO followed by DI
- Notes
- The base stage of most laboratory systems
ASTM D1193 limits as commonly published. Confirm against the edition your SOP cites.
Selection guidance
Use Type III for volume duty and stop paying to over-purify glasswash
Laboratories routinely run glassware washers and autoclaves on Type I or Type II water because that is what the system dispenses, and the cost lands on polishing packs and cartridges that exhaust far sooner than they should.
Take a volume audit: work out how many litres a week go to washing, autoclaves and baths against how many go to analytical work. In most laboratories the split is heavily toward the former, and feeding those uses from the Type III stage directly extends the life of every consumable downstream.
Application mapping
Where Type III RO Water Systems Are Used
Glassware washing
- Typical requirement
- Final rinse water free of scale-forming ions
- Indicated configuration
- Type III direct from the RO stage
Autoclave feed
- Typical requirement
- Low hardness to protect the chamber and lines
- Indicated configuration
- Type III with storage sized on cycle demand
Reagent and buffer make-up
- Typical requirement
- General laboratory quality
- Indicated configuration
- Type III, or Type II where TOC matters
Feed to higher grades
- Typical requirement
- Base stage for Type I and II production
- Indicated configuration
- RO module feeding DI and polishing stages
Replacement and consumables
Replacement Intervals and the Signs It Is Due
Intervals are indicative planning figures. The signal in the last column is what should actually trigger the change.
| Item | Typical interval | Signs it is due |
|---|---|---|
| RO module | 2–3 years typical in laboratory duty | Output conductivity rising, flow falling |
| Pre-filter | 4–12 weeks | Differential pressure rise or flow decay |
| Carbon pre-treatment | 3–6 months | Free chlorine detected downstream |
| Storage tank vent filter | 6–12 months | Scheduled — protects the stored water |
RO module
- Typical interval
- 2–3 years typical in laboratory duty
- Signs it is due
- Output conductivity rising, flow falling
Pre-filter
- Typical interval
- 4–12 weeks
- Signs it is due
- Differential pressure rise or flow decay
Carbon pre-treatment
- Typical interval
- 3–6 months
- Signs it is due
- Free chlorine detected downstream
Storage tank vent filter
- Typical interval
- 6–12 months
- Signs it is due
- Scheduled — protects the stored water
Intervals depend on feed water and throughput. Final intervals follow the datasheet of the system quoted.
Put this on a standing order
Once a plant has a year of running behind it, consumption for this item is predictable. Sending the plant list and last year's usage gets it scheduled against your maintenance calendar instead of ordered in an emergency at the point the plant is already out of specification.
Commercial terms
How This Category Is Quoted
Water treatment does not have a list price, and any supplier quoting one before seeing a feed analysis is quoting a different plant from the one you need.
Pricing basis
On request, and capacity-dependent. Plant pricing moves with capacity, feed water analysis and the recovery target; membranes, cartridges and resins are quoted per element, per lot or per litre of media.
Order quantity
From a single replacement element or a case of cartridges through to full plant scope. Consumable lines are quoted per box or per lot, and the lot size is stated on the quotation.
Lead time
Confirmed per line item at quotation stage. Stocked consumable lines and made-to-order plant differ substantially, so a single blanket lead time for the category would be misleading — the quotation carries the figure for each line.
Invoicing
GST invoice against company or institutional purchase order. Proforma issued where advance payment or internal approval requires it.
Delivery coverage
Despatch from Delhi NCR across India, including plant, project and institutional sites. Delivery city and site access are asked for at enquiry because both affect despatch mode.
Documentation
Technical datasheet for the item quoted, and a test certificate where the principal supplies one with that product. Tender and institutional documentation formats are prepared on request — send the format with the enquiry so the quotation is issued in a form you can submit without rework.
Request for quotation
Request a Quote — Type III RO Water Systems
Fields marked with an asterisk are required. The technical fields are what usually decide whether you get a quotation on the first pass or three emails of clarification.
Frequently asked
Type III RO Water Systems — Common Questions
What is Type III water used for in a laboratory?
Glassware washing, autoclave feed, water baths, general rinsing and reagent make-up where analytical grade is not required.
It is also the base stage from which Type I and Type II are produced by adding deionisation, UV oxidation and filtration.
Is Type III water the same as RO water?
In practice the terms are used interchangeably, because reverse osmosis is the usual way Type III is produced. Type III is the specification; RO is the process that meets it.
Where the feed is difficult, an RO module alone may not reach the Type III conductivity limit, and a deionisation stage is added.
Can Type III water be used for HPLC?
No. HPLC and LC-MS call for Type I, and usually a low-TOC configuration of it. Type III permits TOC at 200 micrograms per litre, four times the Type II limit.
Organic carryover at that level shows up directly as baseline drift and ghost peaks.
Related Products and Categories
Specified alongside type iii ro water systems, and the category this page sits in.
Type II pure water systemsRO-DI water systemsCartridge filters for the feed stageBack to Laboratory Water Systems
- Delhi NCR base with pan-India supply, including plant and project sites.