Deionized Water, 18 MΩ, Reagent Grade, ACS Type I

• What it is. This deionized water is reagent-grade Type I water with 18 megohm resistivity, available in 1-gallon, 5-gallon, and 55-gallon drum sizes. It is ion-free, high-purity water for preparing reagents, dilutions, standards, and precision rinsing.
• What Type I means. ASTM D1193 defines Type I reagent water as having a resistivity of at least 18 MΩ·cm and a conductivity no higher than 0.056 µS/cm at 25 °C, with limits of 50 µg/L total organic carbon, 1 µg/L sodium, 1 µg/L chloride, and 3 µg/L total silica in the D1193-99 edition.
• Why 18 megohm matters. Resistivity measures how strongly water resists electrical current; it decreases as dissolved ions increase. Water at about 18.2 MΩ·cm at 25 °C contains essentially no dissolved ions, making it suitable for trace analysis, standards, and sensitive instrumentation.
• How it is made. Type I water is produced through deionization and polishing steps, often combined with reverse osmosis, filtration, and organic removal, reducing ions, organics, and particles to trace levels.
• Resistivity falls once opened. Ultrapure water absorbs carbon dioxide from the air within minutes, forming carbonic acid that lowers resistivity well below 18 MΩ·cm. Packaged water serves applications that need ion-free, low-organic water rather than a guaranteed in-use resistivity reading.
• Laboratory uses. Type I water is used to prepare standards and reagents, dilute samples for ICP, IC, and HPLC, make buffers and mobile phases, rinse precision glassware, and supply instruments and analyzers that require high-purity water.
• Deionized versus distilled. Deionization removes dissolved ions through ion exchange, while distillation removes impurities by boiling and condensing. Type I deionized water reaches far lower ionic levels than single distillation.
• Three sizes. The 1 gallon (ZW0006-128) suits benchtop reagent work, the 5 gallon (ZW0006-640) supports daily lab use, and the 55 gallon drum (ZW0006-999) serves production, rinsing, and high-volume users.
• Where it is used. Reagent-grade water is used in analytical, pharmaceutical, environmental, semiconductor, and research labs, wherever water quality affects results. It pairs with every titrant and buffer in Lab Pro's range, from Buffer Solution pH 7, Yellow to Sodium Hydroxide 0.1N/M, 1 Gallon.

Technical Specifications

Available Variants

• ZW0006-128: 1 gallon for benchtop reagent work.
• ZW0006-640: 5 gallon for daily laboratory use.
• ZW0006-999: 55-gallon drum for production and high-volume rinsing.

Applications / Common Uses

• Standard preparation: Prepares calibration standards and reagents.
• Trace analysis: Dilutes samples for ICP, IC, and HPLC.
• Buffer and mobile phase preparation: Provides ion-free water for buffers.
• Precision rinsing: Rinses glassware and components without residues.
• Instrument supply: Feeds analyzers needing high-purity water.

Storage, Handling & Shipping

Store tightly closed at room temperature, away from chemical fumes and sources of contamination. Open containers only when needed, use clean dispensing equipment, and use opened water promptly, since it absorbs carbon dioxide and contaminants from the air.

• Incompatible materials: None (protect from contamination).
• Personal protection: Standard laboratory gloves to avoid contaminating the water.
• Spill response: Wipe up.
• First aid: Not required under normal use.

Related Categories & Services

• Shop Buffers, Standards & Solutions for related products in this category.
• Explore General Chemistry and ACS Grade Laboratory Chemicals.
• Vendor Managed Inventory (VMI) Program: Lab Pro can stock, track, and replenish this item on site so it never runs out. Contact info@labproinc.com or 888-452-2776 to set up a VMI assessment.

Related Articles

• What Is The Proper Deionized Water Conductivity Range?
• The Importance of Deionized Water in Laboratory Applications
• Deionized vs. Distilled Water: What's the Difference?