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A Perc Test: What It Is and Why You Need One to Build Near Rochester

Posted by John Graziose

Wed, Sep 15, 2021 @ 14:09 PM

A Perc Test- What It Is and Why You Need One to Build Near Rochester-1

If you’re looking for a scenic view, you’ll find plenty of lots that meet your requirements in the Rochester area. Thanks to the abundance of lakes, forests, and undeveloped land in the region, it’s fairly easy to find a building lot that overlooks a lake or pond or backs up to the woods. Although the land may look ideal at first glance, you won’t be able to build on it unless the lot can pass a perc test.

Who Needs a Perc Test? 

Anyone who buys a lot in an area without municipal sewer service needs a perc test before building. The test is performed to determine if the lot can support a septic system to process household waste and grey water. The builder may have already taken care of site preparation, including the percolation, or “perc” test if you’re building a house in a new home community.lots for sale in finger lakes, NY

If you’re choosing and buying a lot yourself, you’ll need to make a successful perc test a condition for the purchase. Without the test, you won’t be able to start construction on your home. A perc test is just one of the land development costs you’ll pay if you plan to build on an unimproved lot. You’ll also need to set a budget to clear the land, obtain permits and surveys, drill a well or tap into the municipal water supply, and run utility lines to your property. 

How Do Septic Systems Work?

Septic tanks are designed to separate solid from liquid waste. Solids sink to the bottom of the tank, while liquids travel through perforated pipes to a leach field. The leach field absorbs, or “percolates” the fluids, which offers a natural way to remove harmful bacteria. Eventually, the purified liquids enter the groundwater.

What Is a Perc Test?

A perc test evaluates how quickly water drains through the soil and helps you decide where to place the leach field. If the water drains too slowly, pools of sewage could pop up on your property.

Quick drainage can also cause problems. When liquids pass through the soil too quickly, there’s no time to filter bacteria and wastes. As a result, the groundwater can become contaminated. If you have a well or spring on your property, you could end up drinking water teeming with bacteria.

Soil quality is a key consideration in selecting a site for the leach field. Soils with plenty of sand and gravel offer the best drainage. Drainage is likely to be poor if the soil is rocky or full of clay.

It’s also important to consider the water table. If the water table is too high, drainage can be affected. Testing during the spring when the water table may be higher due to frequent rains versus testing in dryer fall conditions could affect your results. 

How is a Perc Test Performed? 

Two or more test holes are dug in preparation for the perc test. The holes are located about 40 feet from each other. Four hours or more before the test is conducted, water is run into the holes to pre-soak them.

During the timed perc test, 6” or more water is added to the holes. The engineer, excavator, or health department official times how long it takes for one inch of water to drain from the hole. The tests are usually repeated several times to confirm the results. Acceptable drainage times vary depending on the county or town requirements. Monroe County requires that 85 percent of the holes must drain one inch in 45 minutes.  

What Happens if the Lot Fails the Perc Test?

A perc test failure doesn’t necessarily mean that you can’t build a home on the lot. If the lot is big enough, another area may be acceptable for the leach field. Of course, that may mean that you’ll need to change the proposed location of the house and other buildings. In some cases, you may be able to add sand or gravel to the soil to improve it, which will increase the cost of site preparation.

Are you ready to buy a lot for your new home? In addition to designing and building your custom home, we can help you evaluate lots you’re considering buying and explore site preparation costs for each lot. Contact us if you’re ready to begin building.

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