Short answer: a typical mobile pet grooming truck needs 50 to 65 gallons of fresh water and 70 to 90 gallons of grey water capacity to handle a full service day of 5 to 7 dogs. High-volume operators (8+ dogs/day) or trucks running large breeds need 70+ gallons fresh and 100 gallons grey. Bath-only mobiles can run smaller. Here is how much water each dog uses, how to size your tanks, and what determines whether you need to refill mid-route.
How much water does grooming a dog actually use?
From operator surveys and our own tracking on customer builds, average water consumption per service:
| Dog size | Bath only | Full groom |
|---|---|---|
| Toy/small (under 20 lb) | 3-5 gal | 4-6 gal |
| Medium (20-50 lb) | 5-8 gal | 6-9 gal |
| Large (50-90 lb) | 8-12 gal | 10-14 gal |
| XL (90+ lb) | 12-18 gal | 14-22 gal |
Average across a typical mixed route (small + medium + a few large): 7-9 gallons per service. A 6-dog day uses 42-54 gallons. A 7-dog day uses 49-63.
You also need water for:
- Hand washing between services (1-2 gallons per dog)
- Cleaning the tub between services (1-2 gallons per dog)
- End-of-day truck cleanup (5-10 gallons)
Grand total water use on a typical 6-dog day: 60-75 gallons. That includes service water plus hygiene plus cleanup.
Why grey water tanks have to be larger than fresh
You drain everything you used to wash, plus shampoo, plus dirt and hair. Grey water volume is always equal to fresh water volume (you cannot create or destroy water during grooming) but the tank has to be bigger because the grey water includes solid debris. Health and waste-handling code in most jurisdictions requires the grey tank to be at least 15 percent larger than the fresh tank to prevent backup or cross-contamination.
Standard ratios we install:
- 50 gal fresh / 65 gal grey (entry-level, bath-only)
- 50 gal fresh / 75 gal grey (most common)
- 60 gal fresh / 90 gal grey (high-volume operations)
- 75 gal fresh / 100 gal grey (large breeds, year-round)
Industry sizing across builders
What other pet mobile builders typically install:
- Wag’n Tails Pet Pro Van: 38 gal fresh / 53 gal grey
- Wag’n Tails Supreme: 70 gal fresh / 95 gal grey
- Hanvey Sprinter conversions: 40-65 gal fresh, varies by package
- Gryphon Streamliner trailer: 50 gal fresh / 70 gal grey
- Chic Puppy Streamliner: 45 gal fresh standard
- Zion Pet Mobiles standard: 50 gal fresh / 75 gal grey
The smaller-tank builders are betting on shorter routes (3-4 dogs before a refill at home or at a customer’s outdoor spigot). The larger-tank builders are betting on full days without mid-route fills. Both work depending on your route plan.
What determines whether you need to refill mid-route
Three variables:
1. Service density per service day. 4 dogs = small tanks fine. 8 dogs = need bigger tanks or mid-route fill.
2. Average dog size. Mostly toy/small breeds = less water per service. Mostly large breeds = more water per service.
3. Whether you can fill mid-route. If most customers have outdoor spigots and you can refill from their home (with permission), smaller tanks work. If you cannot ask customers, full-day capacity is required.
Most operators we build for spec for a full service day so they never have to ask. Saves the awkward conversation, saves time, more professional appearance.
The end-of-day routine
Mobile pet grooming is regulated less than mobile food, but waste handling still matters. End-of-day:
- Return to home base or commissary
- Drain grey water at an approved location (your home if zoned for it, or a commercial dump station)
- Refill fresh water tank from a potable source
- Sanitize the fresh tank monthly with a chlorine solution
- Sanitize the grey tank quarterly to control biofilm and odor
Some cities prohibit dumping grey water from commercial vehicles at home. Check your local environmental health department. RV parks, commissary kitchens, and some dog daycares offer dump access for $30-$60/month if you do not have a home option.
Hot water capacity
Separate from raw water capacity is hot water output. Tankless gas water heaters are standard on pet mobile builds. Sizing target: 5-6 gallons per minute output continuous. That is enough for back-to-back services without recovery time.
Storage tank water heaters (10-20 gallon) are an alternative for low-volume operations. They use less propane on standby but can run dry between dogs on a busy day.
For pet grooming specifically, water temperature matters. Most groomers wash at 95-105F. The heater must hit that temp at 4-5 GPM flow rate. Underspeccing means cold rinses on dog 4. Customers and dogs both notice.
Water filtration
Some operators add a sediment + carbon filter on the fresh water inlet. Cost: $80-$200 installed. Worth it if you fill from variable sources (different customer spigots, gas stations, etc.) where water quality may have chlorine, sediment, or hard mineral content. Hard water leaves residue on coats and can stain stainless steel.
How we size pet mobile water on each build
Tell us:
- Target dogs per service day
- Average breed mix
- Whether you have a home dump option or need commercial commissary
- Whether you will fill mid-route or run full-day capacity
We will spec the right tank package and the right water heater for your operation. Get a free quote or call 719-722-2537.
Related: pet mobile business guide, generator sizing, cost breakdown.
Ready to build your truck?
We design and build custom food trucks and trailers compliant with the regulations on this page. From a single phone call to keys-in-hand in 6 to 8 weeks for most builds.
Built in Woodland Park, Colorado. Delivered to operators in CO, AZ, NE, MT, and WY.