Selecting the right water supply piping is crucial for any construction or renovation project. The type of piping you choose impacts water flow, water pressure, longevity, and maintenance requirements. This guide will walk you through the key factors to consider when choosing water supply pipes.

Introduction to Water Supply Piping

Water supply pipes carry fresh water from the main line into homes, businesses, and buildings. They distribute water throughout the structure to supply faucets, appliances, plumbing fixtures, sprinklers, and more.

Choosing the right piping material and size is essential for:

Ensuring adequate water flow and pressure to meet needs
Preventing leaks, bursts, and other problems down the road
Providing long-lasting and reliable performance
Keeping maintenance requirements and costs low

The main options for water supply piping include:

Copper: The traditional choice, provides excellent durability if properly installed. Available in different thickness levels.
PEX: Flexible plastic piping that is more affordable and easier to install than copper.
CPVC: Rigid plastic piping that handles high temperatures but can become brittle over time.
Galvanized steel: Durable but prone to build-up and corrosion over time.

Many factors come into play when selecting the right piping material and size, which we’ll explore in this guide.

Determine Your Water Demand Needs

The first step is gaining a clear understanding of your expected water usage needs. This determines the required pipe size to deliver adequate flow and pressure.

Consider:

Number of fixtures: How many faucets, toilets, showers, appliances, etc. need a water supply? The more fixtures, the greater the demand.
Peak usage times: When will water demand be highest? During morning and evening in a home; different times of day for businesses.
Flow requirements: Fixtures have recommended water flow rates – a showerhead may need 2.5 gallons per minute (GPM), for example.
Pressure needs: Target pressures range from 45-80 PSI for most homes. Insufficient pressure can result in weak flow from fixtures.

Document all expected water-using fixtures, their locations, and their flow rates. This is crucial information for proper pipe sizing. Getting an accurate idea of peak demand ensures adequate pressure and flow during the busiest times.

Choose a Piping Material

With your water demand known, you can zero in on choosing a piping material that suits your needs.

Copper

Copper has been the go-to choice for water supply plumbing for decades. It offers numerous benefits:

Durability – Copper is highly durable and corrosion resistant inside and out. Properly installed copper piping can last 50 years or longer.

Resists scale buildup – Smooth interior surface prevents limescale and mineral deposits from accumulating over time.

Withstands pressure – Excellent material strength to withstand water pressure surges.

Variety of sizes – Available in a range of standard pipe sizing to meet flow needs.

Reusable – Old copper pipes can be salvaged and recycled.

Drawbacks of copper include:

Expensive – Higher material costs compared to plastic piping.
Rigid installation – Difficult to snake copper pipes; soldering required for connections.
Prone to pitting – Copper can develop pinholes and pitting when exposed to acidic water or water with excessive mineral content.

Overall, copper remains a top choice for water supply lines in many homes and buildings. Using thick, Type L or Type K copper will provide enhanced durability.

PEX

PEX (cross-linked polyethylene) has surged in popularity as an alternative to copper piping. Key advantages of PEX include:

Affordable – PEX costs significantly less than copper.

Flexible – Its flexibility allows PEX to snake around obstacles easily.

Fewer connections – Long PEX lines reduce the number of fittings needed compared to copper.

Easy to install – No soldering required; uses simple crimp or clamp connections.

Freeze resistant – Can expand and contract with water flow to resist damage from freezing.

Quiet flow – Less prone to water hammer and noise issues than copper.

Disadvantages of PEX are mainly related to its longevity:

Potential leaching – Can leach chemicals into water over time, especially with acidic water.
Sunlight degradation – PEX breaks down more quickly with prolonged exposure to UV light. Keep covered.
Rodent damage – Susceptible to gnawing damage from rodents.
Lower pressure rating – Pressure ratings around 100 PSI compared to copper’s 400 PSI capability.

PEX offers a quicker, simpler, and less expensive piping solution in many low-pressure applications. Take measures to prevent UV and rodent exposure for best results.

CPVC

CPVC or chlorinated polyvinyl chloride piping shares some similarities with PEX as a plastic alternative to copper. Key features include:

Inexpensive – Comparable cost to PEX, much lower than copper.

Rigid – Provides a rigid piping structure like copper.

Corrosion resistant – Excellent corrosion resistance.

High temperature rating – Rated for hot water up to 200°F. Higher than PEX.

Drawbacks of CPVC include:

Prone to cracks – Can become brittle and develop cracks over time as plasticizers leach out.
Difficult repairs – Cracked sections require full replacement.
Lower pressure rating – Maximum pressure around 100 PSI.

CPVC offers a cost-effective alternative to copper for both hot and cold water supplies. But its potential to develop cracks over time is a notable downside.

Galvanized Steel

Galvanized steel piping was commonly used in older homes. It offers:

Affordable – Lower material cost compared to copper.

Strong – High strength and pressure capacity.

Drawbacks are significant:

Corrosion – Interior corrodes over time, restricting water flow. Exterior can corrode if underground.
Scale buildup – Promotes lime and mineral deposits internally.
Challenging repairs – Difficult to cut out and replace small sections if damaged.
Toxic when welded – Gives off zinc fumes when welding.

Galvanized steel should not be used for new water supply systems today given its potential corrosion and scale issues. Consider replacing galvanized lines in older homes.

Lead

Some older homes still have lead pipes, which pose a dangerous health hazard due to lead leaching into drinking water.

Lead piping should be completely avoided or fully replaced if present in an existing water system.

Determine Required Pipe Size

After choosing a piping material, properly sizing the pipes is crucial. Several factors determine the right size:

Expected peak water demand
Number and types of fixtures
Length of piping runs
Elevation changes along the piping route

Smaller diameter pipes are less expensive but can limit water flow, especially over longer distances. Oversizing is better than undersizing.

The required pipe size can be determined in a few ways:

Fixture Method

Total up the required flow rates for all fixtures based on their ratings. This provides the peak demand flow rate.

Use published sizing tables to choose a pipe size adequate for the total fixture flow rate and piping system specifics.

This method provides a rough estimate but doesn’t account for pressure loss over distance.

Pressure Loss Method

Determine the acceptable pressure range in the system (typically 45-80 PSI).

Calculate the pressure loss per foot run for each pipe size at the desired peak flow rate using friction loss equations.

Choose a pipe size that keeps pressure loss within the acceptable pressure range over entire piping lengths.

This more involved approach provides a highly accurate pipe size, but requires flow rate and pressure loss calculations.

Software Programs

Specialized plumbing software like Elite Software optimally sizes piping systems after inputting fixture requirements, layout, and other specifications.

The software models real-world system conditions for the most accurate pipe size selection.

Easy to learn and use. Allows quickly generating optimized designs.

Choose Reliable Fittings and Valves

The joints and fittings used to connect piping are crucial for integrity and leak prevention. Use the following quality fittings:

Copper:

Soldered joints for most reliable copper connections
No push-fittings like SharkBite – higher risk of leaks

PEX:

Brass or copper crimp or clamp fittings only
Avoid cheap plastic fittings that can crack under pressure

CPVC:

Threaded or solvent-cemented schedule 80 CPVC fittings
Match sizes and ratings exactly

Additionally, always install full port ball valves for all fixtures for isolation capability in case of leaks. Gate valves and globe valves should not be used.

Investing in reliable, well-matched fittings and valves prevents headaches down the road.

Ensure Proper Installation

Adhering to codes and best practices during installation is just as important as material selection. Key guidelines include:

Shutoff valves – Install a separate shutoff valve for every fixture and appliance leaving the main line. Allows isolating specific areas for maintenance.

Hangers and supports – Use appropriate hangers to securely attach supply pipes to structural members. Follow specified hanger spacing based on pipe size and type.

Insulation – Insulate cold water pipes in unheated areas to prevent freezing. Insulate all hot water pipes to conserve heat.

Sloped layout – Slope horizontal piping runs ≥ 0.25 inches per foot to allow air to escape and drainage of pipes.

Proper burial – When burying supply pipes, use proper backfill materials and depths to prevent damage.

There are many nuances to proper supply piping system installation. Follow all applicable codes as well as manufacturer specifications for the selected piping products.

Maintain Your Piping System

The work doesn’t stop once your water supply piping system is installed. Maintaining your piping keeps it operating safely and efficiently over its full lifespan.

Flush piping before use – Flush all new piping with high water velocity to remove any dirt or debris before connecting fixtures.

Regular leak checks – Periodically check for leaks throughout the system and repair immediately if found. Watch for signs like damp areas or dripping.

Water quality testing – For older piping, have water tested for lead and other contaminants. Replace any hazardous piping.

Avoid harsh chemicals – Don’t use solvent cleaners or harsh chemicals that can degrade or corrode piping over time.

Inspect exterior piping – Ensure any underground piping, supports, and insulation remain in good condition.

Update failing piping – If existing piping shows signs of leaks, corrosion, or diminished flow, consider a full replacement.

Proper maintenance extends the trouble-free functioning of your potable water supply system.

Frequently Asked Questions About Water Supply Piping

Choosing and installing the right water supply piping in your building or home is important for ensuring adequate water flow while preventing leaks and other problems. Here are answers to some frequently asked questions:

How often should water supply pipes be replaced?

It depends on the piping material. Properly installed copper piping can last 50 years or longer. PEX piping has an expected lifespan around 25 years. Old galvanized steel typically needs replacement after 20 years or less. Replace any piping that shows signs of leaks, corrosion, or reduced water pressure.

Can different piping materials be combined in a system?

Yes, though use caution when transitioning between piping materials. Ensure connection fittings between different pipe materials are rated for the change. The best practice is to choose one primary piping material for the entire supply system if possible.

How do I quiet noisy pipes and prevent water hammer?

Water hammer from quick valve closure can be prevented by installing water hammer arrestors near problem fixtures. For noisy pipes, securely fasten them to reduce vibration. Avoiding sharp bends and elbows also reduces noise. Insulating pipes helps muffle noisy flow.

Can PEX pipe withstand freezing?

PEX is more freeze-resistant than rigid copper or CPVC, but it can still burst if frozen. Provide adequate insulation and heat tracing on PEX piping in unheated areas to prevent freezing. Never allow water to sit stagnant in pipes exposed to freezing.

How do I prevent galvanized steel piping corrosion?

Unfortunately galvanized steel corrodes from the inside out over time. There is no way to fully prevent the corrosion short of replacing it with a more modern piping material. Attempt flushing the system yearly to remove some mineral deposits.

Should water supply piping be above or below ground?

Outdoor underground installation protects against freezing but makes leak detection and repairs more difficult. Where possible, keep water supply lines inside or take measures to allow visual inspection and prevent corrosion on underground runs. Proper burial depth is crucial to prevent damage.

What is the best material for hot water supply lines?

CPVC plastic piping is ideal for hot water with a temperature rating up to 200°F. Copper resists high heat but is more expensive. PEX piping has a maximum rating of 180°F for hot water lines – ensure hot water heaters don’t exceed this.

How often should I inspect water supply plumbing?

Ideally, visually inspect all visible water supply piping at least annually. Check for corrosion, leaks, sagging pipes, or damage. Also inspect the condition of outdoor buried piping and valves when excavating nearby. Catching minor issues early prevents major breakdowns.

Conclusion

Selecting suitable water supply piping and properly installing the system are challenging but extremely important steps in any construction project. This ensures ample water flow to meet needs while minimizing leaks and other piping problems in both residential and commercial buildings.

Key considerations include reviewing water demand, selecting durable and sized piping, using high-quality fittings, following codes, and performing regular maintenance. Finding the optimal balance of cost and longevity with the piping material choice is also crucial.

With upfront planning, proper product selection, and care taken during installation, your building’s water supply plumbing will provide reliable performance for decades to come. Partnering with professional plumbers and following their recommendations helps ensure you have clean, clear water flowing whenever needed.

How to Choose Water Supply Piping