Struvite is a subject that is commonly included in RV blogs about wastewater. It is often described as one of the leading causes of holding tank issues. But what is struvite, is it as common in RV holding tanks as we are led to believe, and is it really a problem?

What is Struvite?

Struvite is the crystallization of magnesium, ammonia and phosphate. Hard water, which is often supplied at campgrounds, usually contains a high concentration of magnesium. Struvite crystals also form at a pH greater than 7 (with 9 being optimal) and a temperature range of 59 to 86 degrees, typical tank temperatures. And when a greater number of anaerobic bacteria is in a holding tank, they can split urea (from urine) into ammonium. The anaerobic bacteria also raise the pH balance, making the tank contents more alkaline. All of these are a recipe for the formation of struvite. 

Where is it Common?

In wastewater treatment plants struvite is a common and expensive problem. But is struvite as big as a problem in RV holding tanks as bloggers make it out to be? While it does occur in RV holding tanks, it happens less frequently than many online sources claim. Our experience has proven that struvite is more prevalent in certain areas and regions of the country than in others. For example, the southern region of the U.S. seems to be where we see the majority of struvite cases. Why is this? Well, all these areas tend to have hot temperatures and hard water – a perfect formula for struvite. That doesn’t mean you can’t get struvite in other less-hot regions, but our decades of experience helping RVers with struvite has led us to be confident that you’re far more prone to experiencing struvite when consistently camping in hot climates (and allowing your tanks to get too hot, from using too little water in your tanks).  It may also be that since so many RVers gravitate towards warm weather, there seems to be a disproportionate amount of people being affected by struvite. 

Even in the southern part of the country, when struvite is blamed for RV holding tank troubles, if you are experiencing excessive odors or a clogged tank, don’t just assume it’s struvite that’s causing the problem. Odds are the real culprit is usually poop and paper build-up inside the tank and before you hire an expensive service to hydrojet your black water tank, we recommend using a high-quality bacteria- and enzyme-based tank deep cleaner and allowing plenty of time to let it work. It may take a couple of tries and rinses but most of the time this is enough to clear out most waste build-up in a black tank. Of course, if you do believe you have a struvite buildup, hiring a hydrojetting service to professionally remove the struvite is always a good idea!

Signs of Struvite Buildup

The common signals you should be watching for to determine if you have struvite buildup are:

  • Do you see bits of grit, sand, or rocks left behind in the sewer discharge hose or clear fittings after dumping your black tank?
  • Does it feel like your tank doesn’t hold as much capacity as it once did AND you’ve been camping in excessively hot weather AND you are confident your tank isn’t full of compacted poop and paper.

Preventing Struvite

Preventing struvite is normally pretty straightforward. Keep your tanks cool and don’t let waste turn “septic”. Excessive amounts of hydrogen sulfide and ammonia are the root causes of struvite, so you want to avoid these. To do so, just use more water! Hold your foot pedal down longer with each flush, especially when camping in hot climates. Be sure and rinse your holding tank after dumping it as often as possible. Closing the black tank valve after dumping and then filling it completely full and dumping the fresh water can also help to remove left over waste and sediment from the initial dump. Also, be sure to treat your black tank with a strong bacteria + enzyme treatment. Doing these two things will keep hydrogen sulfide and ammonia under control and help prevent struvite buildup. It really is that simple.

The Takeaway

Many RVers assume they have struvite, when they don’t. If you are experiencing common problems like odors, clogs, or misreading sensors, odds are the root of your problem is a buildup of poop and toilet paper, not struvite. If you still think you have struvite buildup in your black water holding tank and have tried cleaning it out to no avail, it may be worth having it hydro jetted by a professional. In some cases, especially with struvite, professional holding tank cleaning services are the best solution. Just be forewarned that not all holding tank cleaning services are created equal. You will want to ensure that the company is using the right equipment to handle cleaning struvite. Typically an electric powered hydro jetter is not strong enough to remove struvite. You should find a reputable tank cleaning service that uses gas-powered hydro jetters that can deliver pressure strong enough to remove struvite. It is a good idea to ask questions before hiring this service. 

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