Introduction

The portable hand wash basin is a safe and convenient sink unit for hand washing where there is no plumbed-in water supply. It delivers a measured quantity of water at a temperature that is just right for effective hand washing. Combined with an anti-microbial soap, its use ensures that hands are clean enough for most operations where personal hygiene is of prime importance. In designing and manufacturing the portable hand wash basin, The Mobile Sink Company Ltd has considered the microbiological safety of the unit itself. A summary of our microbiologist’s analysis of the microbiological safety of the unit follows.

Microbiological Safety

The portable hand wash basin water supply is a closed system comprising a water container, tubing (some flexible and some rigid), an electric pump, a heater and a switch, all of which deliver heated water to the sink via a stainless steel faucet. The heater and the length of tubing in which the water is heated are copper lined.

Because the water supply system is essentially closed, contamination of the supply water with pathogenic or other micro-organisms is not to be expected other than at filling and emptying times. Therefore, careful filling and emptying should ensure clean water is supplied at the tap.

Many scientific studies have demonstrated the inhibitory effects of copper on the growth of a variety of organisms, including bacteria, moulds and algae. The copper in contact with the water being heated can therefore be expected to inhibit the growth of many organisms.

Also, because the clean water container is enclosed in a light-tight cupboard, any light-dependent organisms will be naturally inhibited. Therefore, growth of algae will be inhibited whilst the container is inside the cupboard.
The waste water system comprises rigid and flexible pipes feeding from the base of the portable hand wash basin into a waste container. Water is contaminated during hand washing, so there is some potential for the growth of micro-organisms in the waste container. However, since the container is enclosed in the same light-tight cupboard, light-dependent organisms (such as algae) are inhibited. Residual copper in the water may also inhibit growth and the use of antimicrobial soap for hand washing will enhance the effect.

Because the portable hand wash basin contains stored water, it may be considered a potential source of Legionella bacteria. The bacteria are environmental contaminants and become a problem only when they occur in large numbers in, for example, water droplets or aerosols. The risk in relation to the portable hand wash basin is almost nil, but we have considered it wise to apply some controls ourselves and to advise users to apply some. These are as follows:

• Controlling the release of water spray – the portable hand wash basin delivers a steady stream of heated water rather than a spray, so aerosol production is kept to a minimum. Keeping the tap free from scale will maintain this control.
• Avoiding water temperatures that favour the proliferation of Legionella bacteria – the water is kept cold until just before delivery. (Legionella bacteria multiply best at a temperature similar to human body temperature.)
• Avoiding water stagnation – change the water daily if it is not used up in less than a day. (Also empty the waste container at the same time.) Also, follow the sanitization routines below.
• Avoiding adding anything to the water which would support the growth of bacteria – use only fresh, clean water.
• Keeping the system and the water in it clean. Again, follow the routines shown below.

The unit is microbiologically safe. The user can maintain that safety by following the guidelines for use, cleaning and sanitizing given below.

Filling

• The portable hand wash basin must be emptied and refilled at least daily if in regular use. If it is not in regular use, both clean water and waste containers must be kept clean and dry.
• Remove the clean water container from unit before filling.
• Empty any water left in the container and rinse it out with clean, potable water.
• Fill the container with fresh, cold, potable water.
• Replace the container in the  portable hand wash basin and connect it up to the water delivery system.

Emptying the Waste Container

• Remove the waste container after replacing the clean container.
• Empty the contents into a suitable drain. Avoid creating splashes and aerosols whilst emptying the waste container.
• Rinse out the waste container, preferably with hot water.
• Replace the waste container in the unit and connect up the waste pipe.
• Avoid contamination the contents of the clean water container with the contents of the
  waste water container.

Cleaning the Containers and Pipes

• This operation must be completed once per week. More frequent cleaning and sanitization may be appropriate in situations where the risk is considered high.
• Remove the clean water container from the portable hand wash basin.
• Empty the container and rinse it as before.
• Fill the container with sanitizing solution at the strength recommended by the manufacturer.
• Replace the container in the portable hand wash basin and connect it up to the water delivery system. Operate the tap twice to fill the pipes with the sanitizing solution.
• Leave the sanitizing solution to act for the time recommended by the manufacturer. If no time is recommended, leave it for at least 15 minutes.
• Remove the waste container from the portable hand wash basin and empty it as before.
• After rinsing the waste container, replace it in the unit.
• Clean the outside of the portable hand wash basin and the sink with an appropriate cleaner. A stainless steel cleaner may be used if necessary, but we would recommend a general purpose surface cleaner. It may be necessary to de-scale the area around the waste outlet of the sink and the outlet of the tap.
• After the clean water container has stood for the appropriate time, operate the tap 5 times to run the sanitizer through the system.
• Remove both containers from the portable hand wash basin.
• Decant the sanitizing solution from the clean water container into the waste container.
• Rinse the clean water container thoroughly and refill it with fresh, cold, potable water (as before).
• Replace the clean water container in the portable hand wash basin and connect it up to the water delivery system.
• After the waste water container of sanitizing solution has stood for the required time, empty it and rinse it thoroughly as before.
• Replace the waste container in the portable hand wash basin and connect up the waste pipe.
• Operate the tap 5 times to rinse out the pipes.