pH Levels for Water Filtration Systems

Water Filtration pH Chart
A handy little pH chart for your reference.

Water Filtration pH Basics

Any time you’re using an iron filter (such as our Terminox™) on well water and your pH is below 7.0 it is considered acid water by any knowledgeable water technician.  Since the beginning we’ve been taught that a pH of 7.0 is neutral, 7.0 and below is acidic and 7.0 and above is alkaline. And, this is the case, unless you happen to be using an iron filter on well water. Acid water can only be treated with acid neutralizers.® offers many different sizes of Backwashing Acid Neutralizers. You should never consider any “multi-media” filter offered by other water treatment companies that are marginal at best.  Your options for acid neutralizers are Backwashing Acid Neutralizers that contain a single media (mineral) such as Calcite or Calcite plus and Chemical Feed injection systems with soda ash (sodium carbonate not sodium bi-carbonate also known as “pot ash”).


Water Filtration Soda Ash
Soda Ash is used in some cases to bring up low pH levels.

My pH is 6.8 and I was told by the in-home salesman that my pH is good.
Your pH is not good and your water is in fact acidic and in need of neutralizing. The best option for you in this case would be a Chemical Feed pump that would inject soda ash into your water line before the pressure tank. The Chemical Injection system is a relatively simple piece of equipment composed of a pump, a mixing tank, and an injector with hoses.  Neutralizing acidic water is quite simple with the Chemical Feed, on average, once a month you would mix soda ash with water. The cost of soda ash is 50 pounds for $50 and on average will last an average household a year or more.   We recommend the chemical injector because it can double up as a chlorinator. The same pump can take care of iron bacteria, which is another common well water problem. On average, you mix 3 to 6 pounds of soda ash to 15 gallons of water.  A Calcite Backwashing Acid Neutralizer is an option, but if you also need to take care of iron bacteria the Chemical Injection system would be best, and there’s no need for the neutralizer tank since Chemical Injection will treat pH from 6.0 to 7.5.  Acid neutralizer tanks are not adjustable since they contain a set amount of mineral that once absorbed pH is what it is. You should always test the pH after the Backwashing Acid Neutralizer Also, pH is critical to test before running the water into your Terminox ISM. Acid water will “burn up” the natural oxidizing mineral.


Chemical Feed Pump for Water Filtration
Chemical Feed Pump

My pH is 6.5 and I was told that I need an acid neutralizer tank.
In this situation it would be OK to install a Backwashing Acid Neutralizer, but the best option would be the Chemical Feed pump.  Backwashing tanks need the mineral to be replaced about once a year depending on your water usage.  We offer EZ fill tanks that are easy to refill with Calcite or Calcite plus.  You should still at this point consider the versatility of the Chemical Feed system, but if maintenance is an issue then a B.A.N is the right choice.  If your pH is under 6.0 the correct way to treat your water is to install a backwashing tank and compliment it with a Chemical Feed pump just in case one tank does not neutralize your water.


Backwashing Acid Neutralizer for Water Filtration
Backwashing Acid Neutralizer

My pH is in the range of 4.5-5.5.
The correct treatment would be to install two Backwashing Acid Neutralizers, one with Calcite plus to be followed by a Calcite tank.  (Tank size depends on flow rate, to determine your flow rate please visit our Articles & FAQ’s and read item number 7.)  An average size is a 10” x 54” 1.5 cubic foot B.A.N.  Our acid neutralizers come with digital Autotrol control valves.  These valves automatically backwash at a set time of 2am, but can be altered to suit your lifestyle.  Backwashing is necessary so the mineral doesn’t harden and become useless. The energy savings that some companies offer with their non-electric valves does not equal the importance of proper backwash. Non-electric valves do not offer proper pressure and length of time appropriate to keep the mineral at its optimal performance.

NOTE: The proper way of treating acid water is your choice, but please follow our advice, we always keep the customers best interest at heart and recommend only the best and correct equipment. The complexity of Backwashing Acid Neutralizers or setting up Chemical Injection requires careful directions and our expert technicians are always available 7 days a week, even on holidays.  


Effects of acid water

  • Green or blue stains in the bathroom sinks, bath tubs, showers, and appliances.
  • Metallic taste if copper pipes are used in the home.
  • Causes problems with PVC and PEX plumbing.
  • Damages the Alkalinity balance of our internal body.
  • Damages teeth.

The proper treatment for pH is important since acidic water can affect our health, homes and plays a big role in the performance of iron, sulfur, and manganese treatment.

When considering acid neutralizers, backwashing tanks with single media are best.  We are always on the cutting edge of technology.  Minerals used in our neutralizing tanks and iron filter units, never use harsh chemicals that others need for regeneration.  Greensand filters are a thing of the past and they should remain there. Our Chemical Feed systems in conjunction with Terminox™ are a one, two punch that is not matched by any other company out there today.  Please call our expert water technicians for free advice at 1-800-684-0979.  They will never ask you to buy anything, but will offer the best advice in the nation!

-Water Filtration Wizard


4 Comments on “pH Levels for Water Filtration Systems

  1. Have been told by culligan the pH us very low 4.5 they recommend a 3000 mechanical feed system. Is there a cheaper answer in your opinion?

    • Firstly, you should double-check the pH with a reputable lab before you proceed. A lab that DOES NOT sell any sort of water filters or equipment. Sometimes local dealers get it wrong. It is common to get a marginal reading on such a low pH. When you take the sample to a lab, be sure they test the FRESH sample “When you come in the door”. A pH sample that sit for any excess amount of time can change. It usually will read LOWER than it really is. Normally, if your pH is truly 4.5, which is rare, you would need TWO backwashing acid neutralizer tanks. One to get the pH up where you can manage it, and the other to get it the rest of the way above 7.5. Be VERY wary of anyone who would use a chemical feeder with a pH increaser called “caustic soda”, as it will likely harm other water filters and devices over time, creating expensive in-home service calls from local dealers. Please do not hesitate to call and speak with a friendly water tech at 800-684-0979 for a discussion of your situation. Don’t worry, they are not allowed to ask you to buy anything or pressure you in any way. They just give you great advice. Also, if you have copper pipes in the home, a pH of 4.5 would almost certainly leave blueish or greenish stains in your sinks or appliances. If you have copper pipes, and you do NOT see any blue or green staining around the home, it is unlikely your pH is as low as you think it is. Get it tested by an independent source. Take care..

  2. I purchased a iron filter and soda ash injector system from you in Nov 2016, how long does media last. It was a 8inch tank

    • Terminox filters can last many many years when properly applied. It is hard to say in your case without first knowing the particulars. Such as iron levels, pH levels, or the presence of organics or iron bacteria. If you call our US Based tech support hotline for assistance. They can look up your particulars in our customer database and advise you accordingly. But the average life expectancy of a Terminox is 25 years when properly applied. And that is why it is the most popular of all of the different types of iron filters available in the US and Canada. If your filters is working, you should not worry. If it ever appears to start letting iron through, there will be a reason for it. Just call our friendly water techs at the Tech Support Hotline and they will help you. A calls to the support hotline are available to our customers free of charge for a lifetime.
      Take care, stay safe.

Leave a Reply

Your email address will not be published. Required fields are marked *