Pure Water and Purified Water are two concepts with clear differences in water quality standards and application scenarios. The corresponding water treatment equipment also has significant differences in process design, core functions, compliance requirements, and other aspects. The following provides a detailed explanation from three aspects: definition and standards, equipment core differences, and typical applications:
1、 The difference between core definition and water quality standards
1. Pure Water
Definition: Refers to water obtained by removing the vast majority of impurities (suspended solids, colloids, soluble salts, organic matter, microorganisms, etc.) through physical or chemical methods, with a purity higher than tap water, but different scenarios have different requirements for “purity” (there is no unified mandatory standard).
Typical water quality indicators:
Conductivity: usually ≤ 50 μ S/cm (resistivity ≥ 20M Ω· cm) cm@25 ℃）；
Total dissolved solids (TDS): ≤ 10mg/L;
Microorganisms: No mandatory requirement (depending on the purpose, such as drinking pure water requiring ≤ 100CFU/mL);
Core features: Emphasizing “desalination” and “impurity removal”, with relatively relaxed requirements for indicators such as microorganisms and endotoxins.
2. Purified Water
Definition: It is mainly used as “process water” in the fields of medicine, biopharmaceuticals, etc. It has strict pharmacopoeia standards (such as the Chinese Pharmacopoeia, USP, EP), requires the removal of almost all impurities, and has mandatory restrictions on microorganisms, endotoxins, and organic matter (TOC).
Typical water quality indicators (taking the Chinese Pharmacopoeia 2025 edition as an example):
Conductivity: ≤ 2.1 μ S/cm (@ 25 ℃);
Total organic carbon (TOC): ≤ 500ppb (0.5mg/L);
Microorganisms: ≤ 100CFU/mL (online monitoring is required during the production process);
Endotoxin: When used in injection related processes, it should be ≤ 0.25EU/mL;
Core feature: Based on “pure water”, strengthen the control of microorganisms, organic matter, and pyrogens (endotoxins), and comply with GMP (Good Manufacturing Practice) requirements.
2、 The core differences of water treatment equipment
Comparison Dimension Pure Water Equipment Purified Water Equipment
The core processing technology is centered around “desalination and impurity removal”, with typical processes including:
Raw water → sand filtration → carbon filtration → precision filtration → primary reverse osmosis → pure water tank with “deep purification+aseptic control” as the core, typical process:
Raw water → pretreatment (sand filtration+carbon filtration+softening) → secondary reverse osmosis → EDI (optional) → pasteurization/ozone sterilization → circulating pipe network → purified water tank
Key component differences: 1. Pre treatment: conventional sand filtration, carbon filtration (meeting the requirements of reverse osmosis inlet water);
2. Core membrane system: mostly first stage reverse osmosis (desalination rate ≥ 99.5%);
3. Material: Components that come into contact with water are mostly made of 304 stainless steel;
4. No mandatory sterilization or circulation system. 1. Preprocessing: Strengthen the removal of organic matter (such as increasing the precision of precision filters to 1 μ m), reduce SDI (pollution index ≤ 3);
2. Core membrane system: mostly “secondary reverse osmosis+EDI” (conductivity ≤ 0.5 μ S/cm), ensuring deep desalination and TOC removal;
3. Material: Components in contact with water must be made of 316L stainless steel (corrosion-resistant, low leaching), with mirror polished inner walls (Ra ≤ 0.8 μ m);
4. Sterilization system: Must be equipped with pasteurization (80-85 ℃ circulation for 30 minutes) or ozone generator to prevent microbial growth;
5. Circulating pipeline network: Fully enclosed circulation (flow rate ≥ 1m/s) to avoid secondary pollution caused by stagnant water.
Online monitoring only requires monitoring of conductivity and liquid level (to ensure that the produced water meets the standards). Mandatory online monitoring: conductivity, TOC (real-time display, over limit alarm), temperature, pressure; Partial scenarios require online endotoxin monitoring; The data needs to be traceable (in compliance with GMP data integrity requirements).
Compliance requirements do not have mandatory compliance standards, only need to meet user water usage indicators (such as enterprise standards for electronics and food factories). Must comply with:
1. Pharmacopoeia standards (such as the Chinese Pharmacopoeia and USP);
2. GMP standards (such as equipment material certification, cleaning validation, process validation);
3. Traceability (all parameter records must be kept for at least 5 years).
3、 Differences in Typical Application Scenarios
1. Application of pure water equipment
Electronics industry: electronic component cleaning, semiconductor lithography (requiring low ion content to avoid short circuits);
Food and beverage: production of bottled water, beverage preparation (to remove impurities and odors and improve taste);
Laboratory: General chemical experiments, instrument cleaning (not strictly required for microorganisms);
Industrial cooling: Boiler feedwater (low hardness, low salt content, to prevent scaling).
3、 Differences in Typical Application Scenarios
1. Application of pure water equipment
Electronics industry: electronic component cleaning, semiconductor lithography (requiring low ion content to avoid short circuits);
Food and beverage: production of bottled water, beverage preparation (to remove impurities and odors and improve taste);
Laboratory: General chemical experiments, instrument cleaning (not strictly required for microorganisms);
Industrial cooling: Boiler feedwater (low hardness, low salt content, to prevent scaling).
2. Application of purified water equipment
Pharmaceutical industry:
-Production of oral preparations (such as ingredients and cleaning for tablets and capsules);
-Injection production (such as cleaning of infusion bottles, dilution of drug solutions, and control of endotoxins);
-Medical equipment cleaning (such as rinsing before disinfection of surgical instruments).
Bioengineering: vaccine production, cell culture (without microbial contamination and toxins);
High end medical: Dialysis water (must meet AAMI standards, endotoxin ≤ 0.03EU/mL).
summarize
The core difference between pure water equipment and purified water equipment is that pure water equipment aims to “desalinate and remove impurities” to meet the high-purity water needs of general industrial or civilian use; Purified water equipment, on the basis of pure water, meets the strict requirements of “no microorganisms, no pyrogens, and low organic matter” in the fields of medicine and biology through strengthened pretreatment, deep desalination, sterile control, and compliant design. When selecting, it should be determined based on specific industry standards (such as whether it involves drug production) and water quality indicators (such as TOC, endotoxins), and should not be used interchangeably.
Post time: Jul-29-2025