Bookmark and Share


Frequently asked Questions about Wells and Drinking Water

1. Why do I need to continue to test my drinking water periodically?
2. What do I need to test for if I am using an individual water system?

3. How often do I need to test my drinking water?
4. What do I need to do if I am buying property that has a well?
5. What if my water is:

     (a) orange

     (b) turbid (cloudy)

      (c) silty 

    (d) not being produced by the well?

6. Should I just be testing my water for the contaminants that are being regulated?


1. Why do I need to continue to test my drinking water periodically?
Actual events of drinking water contamination are rare, and typically do not occur at levels likely to pose health concerns. However, as development in our modern society increases, there are growing numbers of activities that can contaminate our drinking water. Improperly disposed-of chemicals, animal and human wastes, wastes injected underground, and naturally occurring substances have the potential to contaminate drinking water. Likewise, drinking water that is not properly treated or disinfected, or that travels through an improperly maintained distribution system, may also pose a health risk. Greater vigilance by you, your water supplier, and your government can help prevent such events in your water supply. Contaminants can enter water supplies either as a result of human and animal activities, or because they occur naturally in the environment. Threats to your drinking water may exist in your neighborhood, or may occur many miles away. For more information on drinking water threats, see

 2. What do I need to test for if I am using an individual water system? 

            Santa Cruz County Environmental Health Services requires that individual water systems be tested for chloride, nitrate, total dissolved solids, coliform bacteria, iron, and manganese. Test private water supplies annually for nitrate and coliform bacteria to detect contamination problems early. Test them more frequently if you suspect a problem. The maximum limit for contaminants regulated by the county is listed in the Individual Water System Guidelines and Instructions.

In addition to the contaminants listed above, you may also consider testing your well for pesticides, organic chemicals, and other heavy metals before you use it for the first time. Be aware of activities in your watershed that may affect the water quality of your well, especially if you live in an unsewered area. A list of contaminants that have National Primary Drinking Water Regulations can be found at 

 3. How often do I need to test my drinking water?

We recommend you test your well for total and fecal coliform bacteria prior to use.

The following is offered as a guideline for testing existing wells:


     •Bacteriological tests should be run at least twice a year, if you have an unsealed well. On a sealed well, once every two years is recommended.

     •Volatile Organic Compounds and Pesticides should be run at least every 3 to 5 years if the well is located in an area where those constituents are a known concern due to surrounding land use practices or naturally occurring compounds.


      •Nitrates and Metals should be run at least once every five years if your well is located in an area of concern about high nitrate levels.


4. What do I need to do if I am buying property that has a well?

If you have bought property that has a well, there are a number of possible issues to address. Is the well a shared well that is jointly used by other households or is it an individual well? And is this properly noted in escrow? The land also needs to be surveyed to see if there is only one well on the property. The well needs to also be checked if it is sealed properly. If the previous owner had kept well logs then these should be reviewed to check the status of the well. The yield should be noted and tested for as well as the existence of contaminants. If you wish to use the well as your water supply, then testing must be done to check the existence of nitrates, chloride, coliform bacteria, total dissolved solids, iron, and manganese. A list of additional contaminants to test for is listed at If no previous log exists then testing should be carried out immediately before use of the well. In addition to answering these questions, you should review Individual Water System Guidelines and Instructions.


5. What if my water is:


This may indicate that your water has high levels of iron. If your water quality reports indicate this then you should consider oxidizing filters as a water treatment system. Ozonation and chlorination could be possible follow-ups to mechanical filtration or an activated carbon filter. All systems would need to be properly maintained and a water treatment professional should be consulted before making a decision.


(b) turbid (cloudy)?

Suspended particulates can cause the water to appear cloudy. Detergents or septic or sewage waste may also be to blame. Additional testing should be done to determine what type of contaminant may be the cause. Then a water treatment professional should be consulted as to the proper treatment of the water.


(c) silty?


 If your water is silty then you may have an improperly constructed well or a hole in the screen or well. If this is the case your water contractor should be contacted as this silt, sand may damage your well pump, water softeners, plumbing, faucets, and many household appliances.



(d) not being produced by the well?

If you turn on the tap, and no water comes out, the problem may be electrical in nature, or the pump may have burned out. If this is the case, call a licensed pump installation contractor. Licensed contractors have experience with pump installation and replacement. If there is a problem related to your pump, the contractor should be able to fix it.

If water pressure has noticeably slowed down over time, but the water is still clear, this could indicate that there is a problem with the pump or your pressure tank. If this is the case, call a licensed pump installation contractor.

If you notice the water pressure has slowed down and there is sediment or grit in the water, or you notice that your pump is running but drawing no water, your well may have gone dry. If this happens you may get a bit of water for a while, but eventually it will stop altogether. In this case, you need to call a licensed well contractor. The contractor can analyze your situation and discuss your options. You might be able to deepen the existing well, or replace the well. The well contractor can assist you through this process.

Any time the pump is removed, replaced, or installed in a deepened or newly drilled well, the well must be disinfected. A water quality test should be completed to ensure that the water is bacterially safe to drink. Additional water quality testing is available if the owner chooses.

After a newly drilled or deepened well has been disinfected, an entire set of water quality testing is required. This includes testing for Volatile Organic Compounds (VOCs).


6. Should I just be testing my water for contaminants that are being regulated?

Although Santa Cruz County only requires testing individual water systems for nitrates, chlorides, coliform bacteria, total dissolved solids, iron, and manganese, you may want to consider testing for other contaminants as well. A number of contaminants as listed in   are regulated in water systems serving more people. Even though these types of contaminants are not required to be regulated in individual water systems, it may be advisable for your health to test for these other types of contaminants occasionally.

There are also the National Secondary Drinking Water Regulations that are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. The list of these contaminants can be found at .

In addition there is a list of contaminants which, at the time of publication, are not subject to any proposed or promulgated national primary drinking water regulation (NSDWRs), are known or anticipated to occur and may require regulations. Even though as of now these have not been found to need regulation, you may still test for some of these possible contaminants. A list of these can be found at