Cold Water Test for Water Cooler Dispensers

This test is part of Water Cooler Dispenser Test Method v1.0

When trying to find the best water cooler dispenser for your home or office, cold water is often the main consideration. A busy office or workspace has a particularly high demand for cold water throughout the day. Our simple testing procedure makes it clear how much cold water you can get per hour at a reasonable drinking temperature.

Best Temperature for Dispensing and Drinking Cold Water

The science behind drinking cold water is a lot less settled than that of hot water. Some people prefer their water extra chilled.

Many health proponents say water between 54‒63°F (12‒17°C) is the best for hydration as well as providing a balance between refreshing coolness and taste.

At least one study has shown that water at 60°F (16°C) is optimal for rehydration. Dispensing water at 54°F (12°C) allows for a gradual increase in temperature to 60°F (16°C) (if not drunk immediately).

For this reason, we established our temperature benchmark as 50‒54℉ (10‒12°C) and this benchmark was also well-supported by our test data.

Our Cold Water Testing Procedure

For our cold water test, we first dispense 10 fl. oz. (300 ml) of water every 3 minutes from each machine and measure ongoing temperature fluctuations. We continue this for over an hour or until the working pattern of each machine has been established.

If a machine is unable to maintain a base temperature of 50‒54℉ (10‒12°C), we increase the time window until a stable hourly working pattern has been established. In this way, we are able to determine how often you can dispense water and how much per hour.

We chose 10 fl. oz. (300 ml) for a couple of reasons. First, it’s the volume of a medium-sized mug cup. And, while we could easily have justified smaller amounts, this set a higher performance benchmark and helped separate the wheat from the chaff.

Through initial testing cycles, we determined that the best machines maintained temperatures at around 54℉ (12℃) if not disturbed for three minutes or so. This also met our requirements for the best temperature to drink cold water.

Furthermore, dispensing 10 fl. oz. (300 ml) every three minutes works out to 200 fl. oz. (6 L) per hour. This is just enough water to service a working group of 20 people, or an optimal span of control.

Why Six Liters is an Optimal Serving Capacity

A top-performing machine can provide 20 people with 10 fl. oz. (300 ml) of chilled water per hour (as long as servings are spaced out). This is equivalent to a medium- to large-sized glass per person. If done right, that’s 80 fl. oz. (2.4 L) per person per 8-hour working day.

This aligns to the Institute of Medicine (IOM) and Mayo Clinic recommendation of 91 fl. oz. (2.7 L) of total daily liquid intake for women and 125 fl. oz. (3.7 L) for men. The average person consumes most of that water in liquid form 100 fl. oz (3 L) for men and 74 fl. oz (2.2 L) for women per day respectively — the remainder tends to come from food.

Taking into account people’s intake outside of working hours, 80 fl. oz. (2.4 L) per person per working day is a reasonable standard for an office machine.

How We Score Our Cold Water Tests

Our test benchmark is designed to identify those machines that can provide up to 6 L of water per hour dispensed at regular intervals and between 50‒54℉ (10°C‒12°C). So far, we have not found machines that perform much better than this. Machines meeting this high standard are awarded 10/10 for cold water in our scoring and ranking system:

• 200 fl. oz. (6 L) / hour = 20 people = 10 pts

We step the score down based on the number of people each cooler can support. A 1-person reduction in capacity means a half-point reduction in rating:

The cold water test itself counts for 60% of the performance score while the other 40% is allotted to the hot water test. Our hot water testing procedure differs because we focus on the maximum temperature, flow rate, single draw capacity for back-to-back drinks, and serving capacity per hour.

Problems Encountered in Our Cold Water Tests

Initially, our testing parameters demanded intervals of 3 minutes, but we found quite a few machines had trouble maintaining a good baseline temperature.

Since performance depends on other factors such as tank size and cooling capabilities, we increased the test interval by 15 to 30 seconds until a stable pattern was established.

We also found that the first batch pours came out a couple degrees cooler than average. However, even after long resting intervals, most machines did not return to their overnight chills.

Another issue we encountered is that some machines run quite hot when under pressure. In some instances the heat exchange grid at the rear became too hot to touch, but not hot enough to burn.

It is rare, however, that a machine would be under constant maximum performance pressure throughout the day. Most machines do need periods in the day where they can ‘cool off’ and calibrate better.

References

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3762624/ ‒ The effect of water temperature and voluntary drinking on the post rehydration sweating
• https://nap.nationalacademies.org/read/10925/chapter/6 ‒ Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2005). Chapter: 4 Water
• https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256 ‒ Water: How much should you drink every day?
• https://www.thehumancapitalhub.com/articles/Span-Of-Control-Everything-You-Need-To-Know ‒ Span of control: Everything you need to know