Roth FAQ MultiTank (RMT) Septic Tank Fralo Tank

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FAQ - Roth MultiTank (RMT)

Can I use a ROTH tank as a pump tank?
All ROTH tanks are structurally suited to be partially or completely pumped dry. You must check with the State, County and perhaps even municipality where the tank is being installed as the regulations on pump tanks are very inconsistent or, in some cases do not exist. ROTH is the only poly tank manufacturer that allows the use of their tank for pump applications without restrictions. When using tanks as a pump tank, special consideration must be given to anti-buoyancy measures as liquid (which serves as ballast) is removed from the tank.
What is the maximum temperature that the tank can withstand?
140 degrees F is the maximum temperature of influent in the vessel.
Will the tank fade or be structurally compromised by prolonged sunlight exposure?
No. ROTH uses resins that contain a UV inhibitor which is the maximum available on the market.
Can ROTH tanks be used as a grease trap?
Yes. The basic principles of a grease trap operation are identical to those of a septic, which is that solids will collect at the bottom fats, oils and greases (FOG) will rise and accumulate at the top with a clarified effluent between the two layers. Ask the factory for directions on how to apply the tank as a grease trap. You must also check with local code officials on inlet sizes, compartment wall design, traffic rating, and other considerations in order to ensure code and regulatory compliance.
Does ROTH use the same resin as rotationally molded tanks?
No. ROTH utilizes a high molecular weight, high density polyethylene (HMW-HDPE) that has superior structural characteristics to the resins used in rotationally molded tanks.
I have a fork cut in my tank. Can this be repaired?
If the fork cut is above the liquid level, it may be sealed with butyl mastic and installed without concern. Other methods for repairing larger holes are to hire a local plastic fabricator who is familiar with welding HDPE to patch the hole by thermally welding at your yard.
Does ROTH use scrap to make their tanks?
Our tanks are made with a blend of virgin resin, internally generated scrap and select, high grade scrap that we purchase on the secondary market. All scrap material purchased from outside sources is industrial based scrap (no consumer scrap that individual households recycle) and is sampled and laboratory tested for compliance to our specifications. Non-compliant scrap is rejected and returned. ROTH considers itself a steward of the environment both in the products that we produce, the materials we use to produce them and the process by which they are produced. ROTH proudly occupies a large portion of a former Brownfield facility that was formerly and EPA Superfund site. We are even more proud of the fact that our process is the most environmentally sound in the world, we have no air, water or solid waste discharge as a result of our process.
Why are ROTH tanks different colors on the inside and outside, but all the other poly tanks are the same color throughout?
ROTH’s process utilizes a 4-layer co-extrusion process that allows us to color each individual layer a different color. The traditional original ROTH brand tanks were blue on the outside and the other three layers black. Black is used to homogenize the color of the innermost three layers when we are consuming scrap material. The new Roth MultiTanks are black on the outer 3 layers with a virgin (white, non-colored) resin on the inner lining or wetted surface.
How should I store my ROTH tanks?
We recommend storing the tanks upside down to minimize the natural sagging that can occur if they are stored on their feet. As HDPE is a pliable material, the tanks will have a tendency to sag slightly over time. While this does not have any impact on the structural integrity of the tank, storing the tanks upside down will prevent this. The tanks should not be stacked any more than 3 layers high.
What third-party certifications does ROTH hold and what do they mean?
ROTH is third-party certified by IAPMO (International Association of Plumbing and Mechanical Officials) which allows us to mark our vessels with the UPC symbol (Universal Plumbing Code) and by CSA (Canadian Standards Organization). All Roth MultiTanks are NSF 61 listed for potable water service.
My local inspector told me that I needed to have an NSF 40 certification on the tank to install it. Is an NSF certification required for septic tanks?
No. This is a frequent point of confusion. NSF 40 is the prevailing standard for advanced treatment units (usually aerobic). NSF 40 is a complicated and extraordinarily expensive certification to achieve and usually takes up to 24 months to complete. We are not aware of any septage jurisdictions that require an NSF 40 for conventional septic tanks.
Can I use the tank as a potable water cistern?
Yes. Approximately 40 states have adopted NSF 61 as their default regulation for potable water cisterns. The RMT series of tanks manufactured by Roth Global Plastics are NSF 61 certified for use in potable systems. All blue ROTH tanks may be used for non-septic applications other than potable such as water storage, chemical feed, agricultural, rainwater, graywater recycling and other similar applications.
I was told that all poly tanks float because they are so light. Is this true and should I be concerned about using a ROTH tank?

All tanks, including concrete tanks will become buoyant when exposed to high enough groundwater without adequate soil coverage or anchoring. Buoyancy is a very simple calculation that is basically a mass versus volume relationship. Consider an empty one gallon plastic milk jug. Since the volume is one gallon and the mass contained is about 8.2 pounds (the weight of most water per gallon) the buoyant force is simply 8.2 pounds if you ignore the weight of the container. Said differently, it would take 8.2 pounds of force to push and hold that jug under water. Buoyancy is also a linear force, so if the tank is half-full, the force necessary to counteract the effects of buoyancy is half. Buoyancy is easily overcome by one or more of the following:

  1. Making sure the vessel is full at all times, especially during times of seasonal high groundwater.
  2. Installing the vessel with adequate cover to overcome the buoyant forces (about 36" of cover for all ROTH tanks).
  3. Installing the vessel with an anchoring system specifically designed by a licensed engineer for the intended application.
Can ROTH tanks be used above ground or on a trailer for water delivery?
While our tanks are designed for buried applications, they are overwhelmingly strong and resilient. We recommend that a tank be bedded in about 6" of pea gravel should it be utilized in an aboveground installation. The pea gravel can be retained in place by constructing a simple sand-box slightly larger than the footprint of the tank. The pea gravel provides the necessary haunch support. No other special care should be required. The same haunch support would be required if they were to be used on a trailer.
Are the tanks suitable for use with chlorine or other chemicals?
HDPE is one of the most chemically resistant materials in the world. Dilute solutions of most chemicals should not present any problems at all. For concentrated chemical solutions, please contact the factory. Most hazardous materials and wastes are transported and stored in HDPE drums, tanks, and other vessels.
What is the difference between one compartment and two compartment tanks?
The use of single compartment versus double compartment tanks is purely driven by regulations. Most regulations clearly identify what applications require a single versus double compartment product.

I want to install a pump in the second compartment. Is the compartment wall watertight?

No. The compartment wall is not watertight, nor is it intended to be. The compartment wall acts as a sludge baffle, allowing a buildup of sludge on the inlet side of the wall. This allows for more highly clarified effluent to develop in the effluent compartment. If your application (and local regulations) require the ability to pump effluent while maintaining the liquid level of the influent, you need to install two tanks in series.
I know that precast concrete tanks must conform to ASTM 1223. Do ROTH tanks conform to the same standard?

No. The ASTM 1223 specification is very specific to precast concrete tanks. In fact, there exists no comparable ASTM specification for polyethylene tanks. The closest specifications that are recognized or acknowledged by many States are the IAPMO and CSA standards, both of which ROTH is third-party certified to. The specific standards are listed below:

  1. IAPMO/ANSI Z1000-2007 Prefabricated Septic Tanks
  2. CSA B66-06 Septic and Sewage Holding Tanks for Plumbing Systems
I noticed that there is a horizontal rib that goes all the way around the tank. Is this a seam?
No. The rib you are referring to is known as the mold part-line. This rib is formed when the two halves of the mold close and “pinch" the hot polyethylene. The tank is completely seamless and the rib that you mention is part of what gives ROTH tanks their extraordinary strength and material thickness at the very midpoint of the sidewall.
I am getting ready to drill my tank before installation. Where do I drill?
All ROTH tanks (with the exception of tanks being installed in FL, AZ, NE and IL) should be drilled at the "A" dimples with a standard 5" hole saw. The dimples are pre-offset at the factory and will provide a 43" invert at the inlet and a 40" invert at the outlet. Tanks being installed in Florida and Oregon are pre-drilled at the factory. Tanks in AZ, NE and IL should be drilled at the “B" dimples with a 5" hole saw and will result in inlet and outlet inverts of 44" and 42" respectively.
Are ROTH tanks traffic rated?
No. Although ROTH tanks are the strongest poly tank on the market, they are not rated for any vehicular traffic. ROTH tanks are suitable for residential installations only and can easily withstand lawnmowers and normal wear and tear.
What is the maximum burial depth?
Our tanks are third party certified by IAPMO and CSA for a maximum burial depth of 36". Most States limit the bury depth of polyethylene tanks to 36" as well. ROTH tanks are regularly installed to depths of 48" without incident and have been installed as deep as 72". Ask the factory for special instructions on deeper bury applications.
Are the risers watertight once they are threaded together?
The riser joints between the tank and riser and from riser to riser are watertight only after applying our gaskets (sold separately) or a sealant of butyl mastic (sold separately) to the joints per the factory instructions.