How to Calculate Costs on Replacing Outdated Plumbing

Plastic vs. copper pipes is one of your biggest cost decisions

By Glyn Sheridan

Photo by iStockphoto.com

Outdated plumbing is more likely than new plumbing to leak or rupture under today's high-pressure water systems. In addition, if your home has old lead pipes, your family may be drinking small traces of the toxin. Replacing outdated plumbing is expensive, especially if your home's layout features pipes that run through walls or sealed joist spaces. Since replacing outdated plumbing involves tearing out walls, homeowners may benefit from remodeling at the same time they replace the plumbing.

• What You Need to Know
• You'll need a detailed plumbing plan and estimates from plumbers and contractors. You may also need a permit from your local building authority.

Step 1:

Schedule a visit with a plumbing contractor to assess your home's plumbing configuration and to establish areas that will require subsequent remodeling. The plumber will give you an estimate for his work, which will include tearing out the old pipes and installing new ones with new fittings.

Step 2:

Discuss the cost of different types of pipes with your plumber. The main types for drinking and bathing water are copper pipes, the most expensive but the most durable, and plastic pipes (CPVC for hot and cold water, PVC for cold water only); a flexible plastic pipe, PEX is also used. For waste water, there's PVC, cast iron, and another plastic pipe form, ABS. Pipe is priced based on length and diameter and you can quickly get a sense of relative prices with a visit to your local hardware store.

Step 3:

Add the cost of demolition and reconstruction of the areas where the old piping runs behind the walls and floors. A general contractor will give you an estimate for this portion of the work. In addition to new pipes, you may need new drywall and flooring.

Step 4:

Figure in the cost of hauling away the old pipes and the construction debris, if the plumber or contractor does not include this expense in an estimate. Your local waste authority or trash hauler can quote a price for delivery and pickup of a construction Dumpster.

Step 5:

Calculate the cost of new fixtures. While your plumber in some instances can adapt the new plumbing to fit the old fixtures, such as sinks and tubs, this approach requires additional labor, since the old fittings may have rust or may require a difficult water supply or drain configuration. In addition, with new plumbing, you can now install such amenities as a garbage disposal or high-pressure faucets with sprayers.

Step 6:

Subtract the cost of any work you plan to do yourself. Leave the plumbing to the professionals, but lower your costs by painting the new walls or hanging wallpaper.

• Tips & Warnings
• Get more than one estimate from plumbers and contractors.
• Consider replacing the plumbing in one room at a time if you're living in the home.
• If you're replacing lead pipes in your home, ask your water utility if the pipes coming to your house from the water main are also lead. If so, request the utility also replace their pipes, too.
• If your plumbing dates from the first half of the 20th century, it is mostly likely galvanized iron. It's possible to replace old galvanized with new galvanized pipe but not typically done. In any event, don't connect copper and galvanized pipe, as that leads to corrosion.