Which one of the following is a disadvantage of Water Cooled System?

The most significant disadvantage of any water-cooled system within a data center is the inherent risk associated with bringing a liquid into close proximity with sensitive electronic equipment. A leak from pipes, valves, or cooling unit coils can lead to catastrophic equipment failure, data loss, and extended downtime. This risk requires the implementation of costly mitigation measures, such as robust leak detection systems, drip pans, and specialized piping, making it a primary concern for data center designers and operators.

A. All components are located inside the CRAC This is not universally true for water-cooled systems (e.g., systems with external chillers/towers) and, if true for a specific design, could be an advantage in terms of a compact footprint.
B. Condenser water piping loops long distances While long piping runs can increase pumping energy costs and complexity, this is an engineering challenge rather than the fundamental operational risk that water presence represents.
C. Usage of the building's condenser water is less expensive than chilled water This statement describes a potential economic advantage of using a specific type of water-cooled system, not a disadvantage.

1. Ebrahimi, K., Jones, G. F., & Fleischer, A. S. (2014). A review of data centre cooling technologies, operating conditions and challenges. International Journal of Refrigeration, 39, 1-24. (See page 15, Section 4.2.2). The paper states, "The main drawback of any liquid cooling system is the potential for leakage, which can cause catastrophic failure of electronic components." DOI: https://doi.org/10.1016/j.ijrefrig.2013.09.003

2. ASHRAE TC 9.9. (2016). ASHRAE Datacom Series 7: Liquid Cooling Guidelines for Datacom Equipment Centers (2nd ed.). In Chapter 3, "Risk Assessment," the guide extensively discusses the risks of liquid leakage, stating, "The primary risk associated with liquid cooling is the potential for the liquid to leak from the system and come into contact with the IT equipment or other electrical systems..." (p. 21).

3. Stanford University, CEE 223A/CS 316: "Data Center Design" Course. Lecture materials frequently emphasize risk mitigation. Lecture notes on cooling architectures highlight that a primary disadvantage of water-based cooling is the "risk of leaks and water damage to IT equipment," which necessitates robust containment and detection infrastructure. (Reference to general course content on data center risk management).