Introduction and Overview

The traditional method of washing the dishes are in the kitchen sink and it has been replaced by automatic dishwashing machines. Machine warewashing is an essential part of kitchen hygiene.

It is very important for an organization to understand the flow and the number of table wares. These contribute to the majority of the items being washed in the dishwasher because the way the tableware is being handled directly or indirectly influence the entire dishwashing operation. Industrial warewash machine are being used in large and small kitchen of a restaurants, large healthcare facilities or nursing homes and in very large kitchen in the in-flight catering services. The machines are also used for cleaning bakery crates, pots and pans, items used in operating rooms and in laboratory utensils.  This essentially means that we are not only washing dishes and therefore we are mostly talking about ware washing and not about dishwashing

What is the objective of Machine Warewashing?

We consider a long list of things which influences the process of Machine Warewashing (MWW) such as design and maintenance of the machine, selection of appropriate type and model, desired results, cost competitiveness etc. 

Below are the main objectives of Machine warewashings

Good wash results

  • Clean and dry wares
  • Meets local health standards

Reliability of equipment

  • Equipment designed for continuous operation
  • Minimum downtime

Efficient System

  • Smooth production flow from serving to ware wash area to storage or back to serving
  • Labor efficiency


  • Economical in water, energy and chemical usage
  • Serviceable: service and parts availability


How do we achieve optimum wash result?

Optimum wash results can be achieved while we use the four factor of a sinner cycle in tune with each other.

  1. Optimum Temperature

Wash/rinse water temperatures has significant influence on wash results as well as achieving the hygiene results

Hot Water Wash and Sanitizing machine:

  • 65-71°C minimum wash water temp
  • 82°C  minimum rinse water temp


  1. Effective Use of Chemicals
    • Reduces surface tension between food soil and dish
    • Suspension of soil
    • Protect material (wares)


  1. Correct Use of Time
    • Duration of soiled wares exposed to cleaning solution ( wash time of 45-60 Second)
    • Depends on the type of soil
    • Rinse time of 7-15 second

Note: It is in any case wrong to want to achieve high capacity per hour through very short contact times.


  1. Mechanical Action

Optimum pump pressure during wash cycle, total coverage wares during wash system through flooding action, special wash jets

  • 15 - 25 psi flow pressure (rinse)


Basic System Requirements

It is essentially important to review the following requirements before deciding a machine:

Correct machine selection

  • Correct capacity (speed, production rate)
  • Conveyor speed, conveyor width

Correct specifications

  • Door, rack or flight (type of items to be washed)
  • Direction of operation (wash area design)
  • Number of tanks (soil load)
  • Booster and tank heat method (water and power supply, space available, temperature required, volume of washing etc.)

Water Conditions

  • Water pressure available (in-line pressure)
  • Water volume
  • Water quality (Hardness, TDS)
  • Supply water temperature

How can we achieve efficient machine operations?

Principally it is important to understand how a mechanic ware washing machine works as you got to deal with it every day. The mechanical action in a machine has a major role in providing optimum wash results, productivity and cost of washing.

Any washing being manual or mechanical will have below basic steps

Pre-clean –

Pre-scraping is a very important step in the whole warewashing process. The amount of soil deposited into the tanks greatly depends on whether a good pre-scraping has been done or not. 

Pre-scraping actually starts during bussing.  While collecting used tableware from the dining table, removal of leftovers such as food, toothpicks, paper, plastic critical.  This step not only helps to keep excessive soil from reaching the dishwasher; but also it prevents from any breakage due to uneven stacking of tableware.

Improper pre-scrapping makes it difficult to control the amount of soil reaching the dishwasher, hence it is critical that effective pre-cleaning process is in place before wares enters the main wash compartment.


Main-wash -

The main wash compartment has the toughest job. In combination with the chemical it has to wash away all the soil. It is critical to achieving a good results by ensuring that wash tank holds the detergent solution, supply of fresh water with a water-level sensor to maintain sufficient solution with proper drain system. A heating system is associated with the wash tank to keep solution hot and the tank is connected to a powerful centrifugal pump in turn connected by pipes to rotating sprays, situated above and under the wash rack. A Scrap trays to catch any large particles and



The function of a rinse is to remove any chemical residual left as well as soil on the tableware.  This final rinse is normally maintained at 82°C to 85°C to sanitize the dishes. With a dual tank machine, an additional pre-rinse section (sometime called ‘power rinse’) is available to boost the rinsing ability.  Most final rinse is trigger by means micro-switch or timer.  It is important that the final rinse is interrupted when there is no dishes passing through to save water and detergent aw well it acts as a safety device since the water is very hot.

The final rinse spray pattern is essentially important factor towards an acceptable drying.  The water pressure of the final rinse must be at the range of 15 – 25 PSI.  The size of the spray nozzles is calibrated according to the water pressure and volume of water per minute as per OEM specification. The spray nozzles must be free from scale in order to provide a clean “fan like, V shape” pattern. It should be providing sufficient water to rinse.



Normally in high temperature machines it is not necessary to use sanitizer in a machine ware washing since final rinse water is above 82ºC.  Sanitizer is used for a low temperature machines and for manual washing.



Drying is achieved through rinse aid added into the final rinse water. Drying may be divided into two types, ambient air-drying and mechanical dying.

Ambient air-drying is very much dependable on the atmosphere temperature and humidity of the work area.  Proper racking is also an important factor. Good ventilation in the wash area can help improve ambient air-drying. Sometimes an additional fan is added near the exit of the dishwasher to help accelerate the drying time. Ceramics and glasses dry quickly, 30-60 seconds.

Mechanical drying is available in most flight-type machine. A heater-blower is installed as a separate compartment after the final rinse section.  This type of system helps speed up the drying then conventional type of dishwasher.


Please reach out to Diversey Expert team for further details and troubleshooting.