Oregon State University

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Well Going Dry

While changes in an aquifer can result in a well producing less water than in the past, many people overlook the possibility of a pump or well construction problem.

This page will help you determine which of these may be the cause of your problem.

Changes in the Aquifer

Seasonal Highs and Lows in Water Table

  • Water tables often fluctuate naturally from season to season. Find out more on how to track water levels over time at the Measuring Well Water Levels page.

  • In general, the shallower the well, the greater the risk of water levels falling in response to dry conditions. This is because many shallow wells are drawing water from surface (water table) aquifers that are recharged primarily through precipitation.

  • To find out if you have a shallow well, check your well log or contact your watermaster for assistance.

Overpumping

  • The level of water in an aquifer can fall if water is being pumped at a rate that exceeds natural replenishment.

  • Pumping creates a cone of depression in water table aquifers. This localized lowering of the water table can be significant when pumping is excessive. In addition, if the cones of depression for two or more wells overlap, well interference can occur.

  • In some regions, the amount of water in the aquifer is limited due to geology making the groundwater resource especially vulnerable to depletion.

  • Your watermaster can provide more information about the likelihood of overpumping in your area.

Geologic Change

  • Since wells draw water from aquifers below the earth's surface (in some cases, many hundreds of feet below the surface!), the amount and accessibility of this water can be altered by geologic events including earthquakes, volcanoes, and mudslides.

  • In diagnosing limited water problems, consider the possible effects from recent geologic activity.

Pump Problems

Clogging

  • Wells and well components require periodic maintenance to ensure efficiency. Pumps should be adequately screened. In addition, sometimes pumps can become clogged from small bits of debris that have entered the bore hole over time. Contact your well or pump contractor to discuss pump maintenance.

Malfunction

  • While pumps can last for many years, they sometimes need to be serviced or replaced. If you think your pump is not functioning properly, contact your well or pump contractor.

Pump Placement

  • If the water level within the cone of depression drops below the depth of your pump you will be temporarily unable to reach water. Decreased water demand will allow the water level to rise again if the aquifer is not already depleted.

  • In some cases your pump can be lowered to increase access to aquifer water. Consult with a well or pump contractor to determine if this is an option.

Well Construction Issues

  • Decreased well efficiency can sometimes be associated with the following:

    • deposits in the well bore hole (this can occur naturally and over time the deposits need to be cleaned out)

    • a well that was never fully developed

    • inappropriate screening to allow for free water movement (wire wrap screens are usually preferable to slotted screens)

    • bacterial deposits (e.g. iron bacteria)

  • If you know your well is shallow and you have had water supply problems in the past, you might consider deepening your well. If at all possible, contact the original contractor who constructed your well. Your local watermaster can also help determine if your well was constructed according to standards.

  • If your well is unable to meet your domestic water needs you will need to consider either deepening the existing well or drilling a new well. Contact your well contractor or your local watermaster for help.

    • DO NOT attempt to deepen your well or construct a new well without the help of a licensed well contractor.

    • DO NOT pour water from another source into your well. Your well is connected to an aquifer and is not a storage device

Precautionary Measures

  • Note changes in water pressure. Reduced water pressure may be a forewarning of a lowered water table and aquifer depletion. However, keep in mind that loss of water pressure may also indicate well inefficiencies or problems with your pressure tank.

  • Note long-term changes in water depth. Water level changes over time can serve as an early warning sign if your water supply is in jeopardy. If you are interested in learning more about measuring your well water level click here.

  • Contact your well contractor to explore ways of improving well efficiency. Many contractors provide a range of services to assist you in improving your well's efficiency. Depending on your situation, you may not need to deepen an existing well or drill a new one.

  • Talk to neighbors who may be drawing water from the same aquifer. The more information you have about the water level in your aquifer, the better prepared you and your neighbors will be for ensuring that your water needs are met.

  • Protect your pump. If you have not already done so, you can install an automatic low-flow shutoff switch ("pump saver") that will protect your pump in the event of a dry well. This shutoff can be easily installed in the control box for your well pump and typically costs under $150.

  • Additional water storage devices. Storage devices such as above ground holding tanks and underground cisterns may provide needed water while allowing more time for the aquifer to recharge. For more information visit the links provided in the Water Storage section.

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