How to Meet Domestic Cold Water Piping Requirements

The city of Chicago has an abundant supply of natural water, so why should you suffer from the slow rate of water. Plumbing is perhaps the most tedious aspect of MEP engineering. There's more to Chicago's residential plumbing than you might think. Not only does it require highly specific knowledge, but it must also be constructed and installed in accordance with the rules and regulations outlined in the City of Chicago plumbing codes.

To understand how residential plumbing works, it's important to have some idea about pipes in general and cold water pipes in particular.

How are cold water pipes different from other pipes?

There are two types of pipes that make up a conventional residential plumbing system:

• Water supply pipes.
• Wastewater drainage pipes.

The main difference between the two is that the water supply pipes are connected to the main water supply and are therefore under pressure. Cold water pipes are also smaller than drain pipes. These pipes are further divided into hot water pipes, which are directed to the boiler or water heater, and cold water pipes, which supply water directly to the facilities.

Now, in most cases, domestic cold water pipes and hot water pipes are quite similar. The reason simply boils down to pre-existing demand and pressure. Because the cold water pipes are connected to the main supply, the cold water supply to the facility is already available at the minimum flow rate required under the City of Chicago Plumbing Code.

Your cold water pipes comply with the Chicago Plumbing Code.

How to size domestic cold water pipes

Fortunately, the Chicago Municipal Code has established very specific instructions regarding cold water pipe sizes. These standards are derived by measuring “fixture units,” a value assigned to fixtures based on the amount of water they use. Because the size of a pipe impacts flow, sizes were defined based on the device the pipe is to deliver water to.

While you may have to do more research to determine the tubing size for a very specific or unusual fitting, regular fittings generally use ½-inch tubing. This includes bathtubs, kitchen sinks, household dishwashers, most toilets, laundry compartments and individual showers, etc. Fittings used on flush mechanisms, such as the toilet flush valve and flush rims on sinks, need to be equipped with a ¾ inch or 1 inch pipe.

If street pressure fluctuates regularly, pipe sizes must be designed to take into account the minimum possible street pressure. However, in cases where the street pressure is below the pressure required by section 18-29-604 of the Chicago Plumbing Codes, you will have to install a water pressure booster or filter in accordance with section 18- 29-606.5 of the Plumbing Code, as variation in sizes can only get you so far.

Maximum flow rates for plumbing fixtures as mentioned in the plumbing code.

Home cold pipe networks are the lifeblood of all plumbing systems. Therefore, to have better access to water flow, the building's water distribution system must be designed to have a minimum pressure available.

You will find the indicative (not exhausted) list of minimum size as mentioned in section 18-29-604.5.1 of the plumbing code below:

Types of cold water pipes

The Chicago Department of Administrative Hearings, Rules and Regulations has specified certain types of piping as suitable for domestic use based on the material from which they are made. Without going into specific grades and varieties, the five materials you will typically find on the market are copper, iron, brass, PVC, and galvanized steel.

For domestic cold water plumbing, here are the approved types of pipe material.

• Copper

Copper or copper alloys come in three varieties based on thickness; type M, type L and type K, in order of increasing thickness. These types are approved by ASTM B 74, ASTM B 447 and ASTM B 251.

• CPVC

CPVC or Chlorinated Polyvinyl Chloride is a variant of PVC used specifically for hot and cold water pipes. Local codes require that PVC pipe pressure ratings be stamped on one side. This type must comply with ASTM D 2846, ASTM F 441, and CSA B 137.6.

• Galvanized steel

Construction trends have recently moved away from the use of steel for domestic piping; however, it is not obsolete. Galvanized steel is incredibly strong, making it suitable for areas where pipes are under load. You should only use materials that comply with ASTM A 53.

Materials like cross-linked polypropylene or PEX are still a subject of debate in Chicago, despite their competitive prices, in addition to all of the benefits of CPVC mentioned above.

Regardless, it's best to call your local inspector before deciding which material to purchase.

Protecting your cold water pipes

The Chicago plumbing code requires that all pipes hidden in concrete, gray or any other material containing some lime and moisture content have a thickness of at least 0.025 inches. This is because lime and moisture react with the pipe material, causing corrosion over time. Chicago engineers are also required to design adequate insulation for all pipes in attics, crawl spaces, or on the outside of the building to protect them from freezing.

Your cold water pipes will also need to be protected from breaks. It is best to keep in mind the structural strength of the type of pipe used when designing plumbing systems. It may be necessary to relieve arcing if the piping is under a lot of tension. In cases where galvanized steel or cast iron is not used, it is best to use code-compliant armor plates to protect the pipes from any physical damage.

Most importantly, keep water pressure below 80 psi as prescribed by municipal code. Otherwise, the pipes may start to leak.

Conclusion

A lot needs to be considered when installing a domestic plumbing system in your home, especially when it comes to cold water pipes. While the task of complying with extensive municipal regulations in this regard can be daunting, keep in mind that these codes exist to ensure long-term ease and safety for residents.

When it comes to design and practical applications, always remember to hire professionals who know how to take care of business. But that's no reason not to have all this knowledge at your disposal. Having an in-depth understanding of such systems will not only allow you to take better care of your home, but you will also make more informed decisions.