Close this search box.

What is Sterile Injectable Water? A Deep Dive into the Process


The importance of water in pharma

Water is at the centre of all pharmaceutical operations. Not only is it used as a solvent in the preparation of drugs, but it also has uses in cleaning, sterilization and heat transfer. It is safe to say that if you are involved in a sanitary industry of any kind, not just pharma, water is essential to your operations. You may be using purified water for your clean in place system, pure steam for sterilization in place, sterile injectable water as a diluent, or another grade of water for the several purposes this essential resource has.

Not knowing how to deal with this important resource can make you feel like a fish out of water in any industry with stringent sanitary standards. Additionally, the risks that come with not knowing the ins and outs of purified water systems and the specifications of each grade of water can be very high in pharma. The quality standards are very high and they should be, considering it might be a matter of life or death for the people who use your products.

Water, like any other substance, is capable of attracting contaminants from the air, the equipment it comes in contact with, or the people who work with it. It may collect impurities during its generation, storage, and distribution. This is why high purity water is usually produced on-site in pharma plants, or packaged with the highest controls in place if it needs to be stored for later use, as with sterile water for injection, which is often produced for distribution.

Different grades of water 

Pure water in pharmaceutical and medical applications is absolutely crucial, but not all water used in these industries is identical.

There is potable water – the water that you would drink or use in your cooking. This water is perfectly suitable for domestic use, but it contains a number of “contaminants” in the form of chlorides, bicarbonates and other minerals which make it unsuitable for sterile manufacturing. Potable water is not directly used in pharma production, but it definitely has a use here as feed water for purified water and sometimes for initial rinses in cleaning process equipment.

Sterile injectable water is one of the highest levels of purity water can achieve in the pharma industry. Achieving this level usually involves the water reaching the slightly lower purity levels first. This means that potable water is the feed water for purified water, which feeds bulk water for injection, which is packaged for use as a diluent i.e. sterile water for injection. So before we can understand sterile water for injection preparation, we need to take a look at other grades of water.

Purified water

 Purified water has many uses in pharma. It is used to clean manufacturing equipment. It is used to formulate, process, and manufacture drugs – it is used to produce oral and topical products and to granulate tablets and capsules. It also serves as the feed water for water for injection and for pharma-grade clean steam.

There are a number of processes that stand between potable water and purified water. For starters, feed water needs to undergo a number of stages of pre-treatment before it can be purified. Chlorination is used to remove bacteria and viruses. Softening involves the addition of compounds like hydrogen peroxide and sodium hypochlorite to eliminate magnesium and calcium salts from the water. And dosing helps to eliminate silica, sulfates and carbon dioxide as well as the chlorine that was added during the initial chlorination process. Finally, this pre-treated water may be converted into purified water via reverse osmosis, electro-deionization, or distillation.

Water for injection

Before we get to sterile injectable water or sterile water for injection preparation, let us take a look at water for injection.

Water for injection is the grade of water used to produce small volume parenterals and large volume parenterals. However, this pyrogen-free form of water is not just used to produce parenterals. The vials, caps, ampoules, equipment – basically everything that might come in contact with an aseptically produced drug – is also cleaned using WFI to prevent these items from getting contaminated.

WFI is used to make drugs that are injected into the body intravenously, subcutaneously or through intramuscular administration. This means that it comes directly in contact with patients’ bloodstream, muscles and tissues. It is no wonder then that water for injection is one of the purest forms of water in pharma operations. WFI uses purified water as feed water; the processes of either distillation or reverse osmosis are needed to produce this highly purified version which is free of pyrogens and endotoxins.

The US Pharmacopoeia, the European Pharmacopoeia and the Japanese Pharmacopoeia all set high standards for the production process, quality and applications of WFI. Water for injection, which is usually produced in the bulk form before it is packaged as sterile water for injection, is tested for appearance, conductivity, bacterial endotoxins, nitrates and heavy metals. Specifically, the US Pharmacopoeia (USP) defines WFI as highly purified water which contains less than 10 CFU/100 ml of aerobic bacteria.

Sterile WFI

Finally, after understanding all the other grades of water, we can begin to understand sterile water for injection preparation. As per the USP, sterile water for injection is sterile, non-pyrogenic, distilled water in a single dose, usually for IV administration. It cannot contain any bacteriostat, antimicrobial agent or added buffer. Since it serves as a diluent for dehydrated medications, it should only be used after a suitable solute has been added. Given the need for absolute sterility, it is only ever supplied in single dose containers.

Sterile injectable water is used to aseptically produce parenteral solutions; it serves as a vehicle for appropriate medications. Nonetheless, due to its hypotonicity, sterile water for injection is a haemolytic agent – this means that it can cause the destruction of red blood cells, leading to the release of haemoglobin. Therefore, it is contraindicated for IV administration without additives.

Ultimately, given the sky high expectations of regulators, pharma and healthcare professionals, and consumers, it is important for your sterile injectable water to be reliable, consistent, and of the highest quality. TSA has been in the process and high purity business for about 20 years and is a trusted name for water for injection generation systems. TSA relies on multi-column distillation plants to help you achieve your high purity needs. With flow rates ranging from 80 LPH to 5000 LPH, construction using high grade stainless steel 316L, and a pre-passivated system, TSA’s WFI systems are ideal for your pharma plant, no matter what its scale.

Share this post:

For 20 years, we’ve been the go-to problem-solvers for high-purity and injectable process applications in the pharma and biopharma industry. We are relentless about continuous process improvement and upskilling, elevating ourselves and our technology so you can get the job done more efficiently with cost optimisations. Use the form below to schedule a call back from our team.

This field is for validation purposes and should be left unchanged.