Not untreated. OSHA requires facilities for flushing and neutralizing spilled electrolyte in battery charging areas, and in Phoenix corrosive wastes must be treated by an approved device before the plumbing system. Discharge to the city sewer also has to stay between pH 5.0 and 10.5, so the drain plan needs approval first.
What does OSHA require around battery charging?
For lead-acid batteries on forklifts, OSHA's powered industrial truck rule, 29 CFR 1910.178(g), covers the charging area. Battery charging installations "shall be located in areas designated for that purpose," and the rule says "Facilities shall be provided for flushing and neutralizing spilled electrolyte, for fire protection, for protecting charging apparatus from damage by trucks, and for adequate ventilation for dispersal of fumes from gassing batteries." It also states that "acid shall be poured into water; water shall not be poured into acid."
Two details matter for plumbing. First, the rule requires the means to flush and neutralize a spill, which puts water, and a place for it to go, in the charging area. Second, OSHA's first aid rule says "Where the eyes or body of any person may be exposed to injurious corrosive materials, suitable facilities for quick drenching or flushing of the eyes and body shall be provided within the work area for immediate emergency use." That is the eyewash and drench-shower requirement; our page on eyewash station plumbing requirements covers the water supply and drain side of it. Whatever flows from a drench station also needs somewhere safe to go.
What stops a corrosive spill from going straight to the sewer?
Two layers: the plumbing code and the sewer authority.
The plumbing code. Phoenix adopted the 2024 International Plumbing Code with local amendments under Ordinance G-7397. Its amended Section 803.1, titled "Neutralizing device required for corrosive wastes," says "The nature of the corrosive or harmful waste and the method of its treatment shall be approved prior to installation." The section applies to "Corrosive liquids, spent acids or other harmful chemicals that destroy or injure a drain, sewer, soil or waste pipe, or create noxious or toxic fumes or interfere with the sewage treatment processes." Phoenix's stated reason for amending it was that "Diluting chemical wastes is prohibited by the Clean Water Act, 40 CFR, 403.6 (d)." The cited federal rule is a ban on dilution, so thinning acid with water is not a substitute for treating it. The waste goes through an approved treatment or neutralizing device, and the method is approved before it is installed.
The sewer rules. Phoenix City Code Chapter 28 bans "Water with a pH less than 5.0 standard units (S.U.) or greater than 10.5 S.U." The federal pretreatment rule sets a similar floor, listing "Pollutants which will cause corrosive structural damage to the POTW, but in no case Discharges with pH lower than 5.0, unless the works is specifically designed to accommodate such Discharges." Spilled electrolyte is acid, so it sits on the low-pH side of those limits until it is treated.
Other Valley cities adopt their own sewer codes with their own limits, so a warehouse in Mesa, Tempe or Chandler should check that city's pretreatment office. The 2024 IPC is the common base, and amendments differ.
How should the drain plan work?
The code language tells you what the plan has to do, and it is a designer's and the city's call how. In practice:
- 1Find out what is already there. Is there a floor drain in or near the charging area? Where does it go: sanitary sewer, storm drain, a sump, or something older? Trace it. Our page on where a loading dock drain goes shows how to trace an unknown industrial drain.
- 2Keep acid away from drains until it is treated. Placing the charging area where a spill can be contained, and keeping it from reaching an open floor drain, is the simplest way to avoid a prohibited discharge. Ask your designer whether a curb, a sump or a neutralization device fits.
- 3Get the treatment method approved. Under Phoenix's amended 803.1, the method must be approved before installation. Ask the city's plan review and pretreatment staff what they want to see.
- 4Plan the eyewash and its drain. The OSHA drench requirement is separate from the spill requirement, and both create wastewater.
- 5Write down who responds to a spill, and what they do. That includes who calls the city if acid reaches a sewer; see what to do after a chemical spill into a sanitary sewer.
If you are adding a charging station to an existing warehouse, check with your city whether the plumbing changes need a permit and plan review. Our page on plumbing work in a commercial tenant improvement explains how that process usually runs.
Do lithium-ion forklift batteries change this?
OSHA's wording in 1910.178(g) refers to spilled electrolyte and to pouring acid into water. A facility that has switched to a different battery chemistry should read the manufacturer's safety data and ask the fire authority and the city what applies, instead of assuming the old charging-room rules still fit or no longer apply. The sewer pH limits apply to any discharge.
What to ask before you build or move a charging area
- Does the charging area drain anywhere, and where?
- Who approves the neutralization or treatment method in my city?
- Is my eyewash or drench shower plumbed to a drain that is allowed to receive that water?
- If acid spills, what is the written procedure, and who has the number for the city's sewer office?
A licensed plumber handles the piping and floor drain work once the treatment method is settled. HQ Plumbing & Air gives free estimates with upfront pricing, is licensed and insured, and offers 24/7 emergency service.