Monitoring and Maintenance of your Water Well

 
 
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 Water level measurements | How to measure water levels | Interpreting water levels | Water quality measurements | Worksheet
Preserving the water source on your farm or acreage is as vital as preserving the quality of your soil.

When we think of factors that limit farm production, what come to mind are land base, finances, time and energy. What doesn’t always come to mind is how necessary water supplies are. Imagine having to reduce the size of a cattle herd or not being able to water your horses because of a lack of water. Water is key to our quality of life as well. Waiting an hour to take a bath or not having enough water to serve two bathrooms would be a change for many families. Proper care and maintenance of your water source are key to protecting your water supply. An effective monitoring program will identify changes in water levels and water quality before they become serious problems. Just like a vehicle needs an oil change, tune up and inflated tires to run properly, your well needs to be monitored, checked and cared for. Regular, systematic inspections and treatment of problems will help increase the life of your well. A licensed water well contractor may be required at times.

In this module you will learn several methods of monitoring your well. A worksheet where you can record your own information is included at the back. The first step in preventative maintenance of your well is taking some simple
measurements. Two measurements that you need to take on a routine basis are:
  • Water level measurements
  • Water quality measurements.
In some areas of Alberta, up to one-third of the new wells licensed are considered marginal or poor for either water quantity or quality. Monitoring and maintaining these wells is key to maximizing the water available and preserving the quality.

Water Level Measurements

Taking water level measurements on a regular basis will tell you whether water levels have changed significantly. In turn, this can help you spot the following problems:
  • Pumping the well at a greater rate than it is designed for (stressing the well by over-pumping)
  • Pumping the well at a greater rate than the aquifer is capable of producing (depleting the aquifer)
  • A plugged screen (or slotted casing) can diminish the well's efficiency and production rate
  • Reducing groundwater recharge due to land clearing and surface water drainage.
It is good practice to take a water level reading monthly or quarterly as shown in the example below. Note in the example that readings were taken both with the pump on and the pump off (with time to recover). Readings taken with the pump on will alert you to any problems with the efficiency of the well (for example, a plugged screen). Readings taken with the pump off will alert you to any problems with the aquifer and the quantity of water available for pumping.


Water Level Measurements Example
Water Level
Time
Pumping
Non-pumping
Comments
3.28 m6:00 am
4.30 m7:45 am
3.31 m6:10 am
4.27 m7:55 am
3.26 m6:00 am

How to Measure Water Levels

There are several devices and methods for measuring water levels:
  • Dip tube
  • Water well sounder
  • Sonic Sounder

Dip Tube
A dip tube can be constructed using a minimum 18 mm (3/4 in.) potable grade plastic pipe or hose that is lowered into the well, to below the pumping water level. It should be taped to the pump line with electrical tape and have a capped bottom with two, 6 mm (1/4 in.) holes perforated on the bottom to let water in and out, allowing it to fluctuate with the water inside of the well. The dip tube should extend down to 1.5 m (5 ft.) above the top of the pump. A measuring device, such as a weighted line or a well sounder tape, can then be lowered inside of the dip tube to measure the water level, with no threat of getting it entangled in the electrical wires or pumping equipment (see Figure 1, Dip Tube). A dip tube can be installed by a licensed water well contractor at the time of construction or, on existing wells during well maintenance.


        Figure 1 Dip Tube

Water well sounder
A convenient method for measuring the water level is to use a water well sounder (also called a water tape). You can purchase one from various suppliers in the province. Although it is relatively expensive, it is a good investment. It’s an accurate and convenient way to take water level measurements.

Sonic Sounder Method
The sonic well sounder is convenient because it does not need to be lowered down the well. It is simple to use for most well constructions and only requires that the well cap be removed. This instrument sends a pulse of sound down the well and records the time required for the sound to echo back from the water surface, using time to calculate the distance to the water level. It is non–invasive and easy to operate but may be more expensive and less accurate than a well sounder.A convenient method for measuring the water level is to use a water well sounder (also called a water tape). You can purchase one from various suppliers in the province. Although it is relatively expensive, it is a good investment. It’s an accurate and convenient way to take water level measurements.

Water well sounders and sonic sounders may be available for sale or rent from water well drilling companies and water well industry suppliers. Tape sounders should be sanitized before and after each use.

Interpreting Water Levels

Once you have an accurate method for measuring water levels, you need to be able to interpret two types of water levels — non-pumping (static) and pumping.

Non-pumping Water Levels
The non-pumping water level is recorded after the water level in the well has been allowed to fully recover and before the pump is turned on. A good time to take a non-pumping reading is first thing in the morning before there has been any water use.

After you have recorded several measurements over a period of time, you can determine if the non-pumping water level in the well has changed significantly. Some change will occur due to seasonal fluctuations. For example, in shallow wells, water levels are usually highest in June or July and gradually decline in late September or October and throughout
the winter.Once you have an accurate method for measuring water levels, you need to be able to interpret two types of water levels — non-pumping (static) and pumping.

Deep wells of 60-90 m (200-300 ft.) do not experience seasonal fluctuations like shallow wells.

Let’s look at some examples and how the results might be interpreted.

Example 1
The table below shows four non-pumping water level readings.
Month
Time
Water Level*
Pumping
Non-pumping
January 1, 20126:00 am3.28 m
April 3, 20125:45 am3.27 m
August 1, 20125:30 am3.30 m
December 1, 20126:10 am3.29 m

*Distance from the top of the casing to water level.

Interpretation: It would appear that there have been no significant changes in the water level over the year so no action is required. The aquifer seems able to supply water to the well at the rate you have been pumping.


Example 2
You look back over your records for the past year and note the following non-pumping water level readings.
Water Level
Pumping
Non-pumping
10.35 m
12.48 m
11.53 m
16.31 m
20.22 m
26.57 m
30.34 m

Interpretation: In this case, you should be concerned. The water level has dropped 20 m over the past year. To address the drop in water level, reduce the amount of water you draw from the well. You can do this by reducing the pumping rate and cutting back on the amount of water use.

Take another measurement in a month to see if the water level is recovering. If you find that the water level begins to rise again, you have been over-pumping your aquifer, producing more water from the well than the aquifer can supply. To prevent your well from going dry, you will need to pump your well at a reduced rate.

If the non-pumping water level suddenly drops after remaining steady for many years, it may be a result of increased use from nearby wells that are completed in the same aquifer as your well.

If the water level does not recover, you will need to:
  • Further reduce water use
  • Look for other possible water sources.

Pumping Water Level
Record the pumping water level while the pump is operating. If you take several readings over time, you will have data that can help you assess the efficiency of the well. When you take pumping water level measurements, you need to be consistent about when the measurements are taken. For example, you might take the measurement after the pump
has been on for 2 hours. Being consistent allows you to compare the readings (see Figure 3, Pumping Water Level Drawdown).


Pumping Water Level Drawdown

Figure 3 Pumping Water Level Drawdown

A good time to take a pumping water level reading is during the day when the pump is pumping, for example, at noon. By then there has been significant water use. Taking the reading at the same time of day will give you comparable water levels, unless water use varies considerably between seasons.

Now let’s look at the significance of some pumping water level measurements.


Example 3
In the table below, six readings were taken after the pump was on for 2 hours.
Water Level
Pumping
Non-pumping
6.67 m
5.23 m
6.34 m
5.35 m
6.29 m
7.02 m

Interpretation: Since the levels are relatively constant, there does not seem to be a problem with the efficiency of the well and no action is required..

Even when the pumping water level remains relatively steady, you need to do regular annual maintenance, including shock chlorination, to control bacteria buildup. If you allow a well to deteriorate for too long, it may not be possible to restore its original capacity.

Example 4
You look back over your records and find that, although the original non-pumping water level has remained constant, the pumping water level has declined.
Month
Time
Water Level
Pumping
Non-pumping
February 1, 201111:30 am20.15 m
April 2, 201111:20 am21.56 m
June 1, 201111:35 am26.26 m
August 3, 201111:45 am28.37 m
October 1, 201111:30 am33.45 m
December 2, 201111:40 am37.20 m
February 1, 201211:50 am40.16 m

Interpretation: The screen (or slotted casing) may be plugged with sand, bacterial growth or mineral incrustation. When this happens, the efficiency of the well is diminished and the production rate (yield) drops.Interpretation: The screen (or slotted casing) may be plugged with sand, bacterial growth or mineral incrustation. When this happens, the efficiency of the well is diminished and the production rate (yield) drops.

If the well yield declines, yet the nonpumping water level remains constant, the well may need to be serviced by a licensed water well contractor. If your well is capable of producing more water than you require, you may not notice a decrease in well yield unless you are routinely monitoring your
water levels.

To correct the problem, hire a licensed water well contractor to determine exactly what is causing the reduced efficiency of the well. The screen (or slotted casing) may need to be surged to remove sediment or in some cases may need to be replaced. You may need to shock chlorinate the well to reduce bacteria or acidize it to remove incrustation on the
casing or screen.

See Module 7 "Troubleshooting Water Well Problems" for more information on well problems.

Water Quality Measurements

Noting changes in water quality is an effective way to monitor your water well. Aquifer contamination, problems with a well's structure, or lack of routine maintenance could each lead to a change in water quality. Use the following checklist as a starting point to determine if a problem exists.

Checklist to Determine a Water Quality Problem
  • Unpleasant odour or taste
  • Red discoloration on plumbing fixtures and fabric
  • Cloudy, dirty water
  • Soap curd on dishes and fabrics
  • Scale in pipes and water heater
  • Salty alkali taste
Some changes in water quality are not detected by changes in taste, smell or appearance. For this reason it is important to sample and analyze your water on a routine basis.

Bacteriological Analysis
Bacteriological analysis determines the total coliform and faecal coliform bacteria in the water. Coliform bacteria are usually present in soil and surface water. Faecal coliform are present in animal and human waste. Both are indicator organisms for the potential presence of pathogenic (disease causing) bacteria. A bacteriological analysis does not test for iron bacteria or sulphate-reducing bacteria which are commonly found in well water. A bacteriological analysis should be done annually.

A bacteriological analysis can be done for minimal cost through your local health unit. This should be done annually.

Chemical analysis
A routine chemical analysis tests for the most common chemical parameters found in water, such as iron, sodium, sulfates, nitrates and nitrites. In some cases, you may need to request testing for additional parameters when a regional health concern is identified (such as arsenic or fluoride).

A routine chemical analysis should be done every two to five years.

Non-routine testing
A routine chemical analysis tests for the most common chemical parameters found in water, such as iron, sodium, sulfates, nitrates and nitrites. In some cases, you may need to request testing for additional parameters when a regional health concern is identified (such as arsenic or fluoride).

Tests for chemical contaminants such as pesticides, hydrocarbons, etc., require special arrangements.

Sampling
How you collect a water sample is as important as the analysis. Proper sampling bottles and procedures are required and can be obtained through your local health unit or private laboratory. Samples not in the proper sampling bottle will not be accepted for testing. Important considerations are:
  • Length of time well is pumped prior to sample taken
  • How sample is stored
  • Length of time for sample to be delivered to a laboratory.
Collect the sample as close to the well head as possible to avoid any effect the water treatment or distribution system may have on the sample. If you want to assess the effectiveness of your treatment system, you will have to take an additional sample.

Check ahead of time with your local health unit or private laboratory for
proper sampling procedures and drop off times.

Interpreting results
Whenever an analysis is done, you will receive a written copy of the results. Keep this information in the front pocket of this manual with your other important papers. It helps to create a history of your well to use for comparison should the water quality ever change. You can also use the analyses to help you decide whether or not any water treatment
equipment is needed to improve your water quality. Local health units are responsible for identifying whether water is fit for human consumption. The Canadian Drinking Water Quality Guidelines published by Health Canada are used to establish when the parameters exceed established maximum acceptable concentrations.

The “Rural Water Quality Information Tool” provides For information on interpreting water quality analysis results. See Module 12 "Other Resources".
 
 
 
 

Other Documents in the Series

 
  Water Wells That Last
Understanding Groundwater
Planning Your Water System
Design and Construction of Water Wells
Water Well Drilling Agreements
Monitoring and Maintenance of your Water Well - Current Document
Shock Chlorination
Troubleshooting Water Well Problems
Protecting Your Well From Contamination
Plugging Abandoned Wells
Groundwater Management
Contacts for More Information about Water Wells
Other Resources
 
 
 
 
For more information about the content of this document, contact Melissa Orr-Langner.
This document is maintained by Deb Sutton.
This information published to the web on May 28, 2001.
Last Reviewed/Revised on March 8, 2013.