At a human milk bank, a lactating woman's breast milk is collected, pasteurised, tested for any microbes of diseases and then stored in a freezer. A strict procedure is adhered to in the collection and dissemination of the milk. The donor mother has to be healthy and off any medication except for health supplements such as iron and calcium tablets. A donor must express milk by using mechanical or electrical pumps that cost about US$1,000 (S$1291).

The expressed milk is pasteurised at 62.5 degrees C for 30 minutes. It is never boiled. Once pasteurised, the milk is rapidly cooled and poured into an autoclave stainless steel container measuring 150cc, 250cc and 300cc, and then preserved at -20 degrees C.

From each of the three containers, a sample is sent for culture and microbiological testing for HIV, history of jaundice, venereal disease and so on. Based on the sample results, disease-free stock is stored and used when required within six months. Depending on the birth weight, a baby needs 40cc to 120cc of milk a day.

During the first few days of delivery, colostrum – a mother’s first expression of milk – is collected and stored separately through a specified procedure. This is given to babies suffering from diarrhoea, malnutrition and burn injuries. Breast milk expressed over the next five to 10 days, referred to as "transitional milk", is also stored separately. The milk expressed and stored thereafter, called "mature milk", contains a comparatively lower protein content.

The milk is preserved in the freezer in steel containers. It can be stored up to three months. Neo-natal intensive care units and premature infants are the most frequent recipients of this milk.