Water and Waste Planning for Office Trailers — Capacity, Service, Equipment
Plan your water supply and waste management before the trailer arrives. Use the formulas and decision trees below to choose the right equipment and service schedule for your site.
Water Consumption Formulas
Water consumption in an office trailer depends on the number of workers and the trailer configuration. Use these formulas to estimate your daily water needs.
Daily Water Formula
6-10 gallons per worker per day
Use the low end (6 gal) for trailers with toilet and sink only. Use the high end (10 gal) for trailers with break room, kitchen, and shower facilities.
Example Calculations
| Workers | Configuration | Daily Water (gal) | Weekly Water (gal) |
|---|---|---|---|
| 4 | Office only | 24-40 | 120-200 |
| 8 | Office + break room | 64-80 | 320-400 |
| 12 | Office + break room | 96-120 | 480-600 |
| 20 | Double-wide + kitchen | 160-200 | 800-1,000 |
Waste Generation Formula
Waste = 70-80% of water consumption
Not all water consumed becomes waste water. Some is lost to evaporation through HVAC, cooking, cleaning, and other uses. For planning purposes, multiply your daily water estimate by 0.75.
Example: A site consuming 80 gallons of water per day generates approximately 60 gallons of waste per day (80 x 0.75 = 60). Over a 5-day work week, that is 300 gallons of waste.
Water Source: City Water vs. Water Box
The decision between city water and a Water Box depends on what is available at your site and the cost of connecting to it.
Use City Water When:
- City water main is within 100 feet of the trailer location
- Connection cost is reasonable relative to project duration
- Project duration exceeds 6 months (cost amortizes over time)
- High daily water demand (12+ workers) makes refill service impractical
Use a Water Box When:
- No city water at the site
- City water exists but connection cost is prohibitive for the project duration
- Project duration is under 6 months
- Site is remote with no utility infrastructure
Waste Disposal: Sewer Connection vs. Waste Box
Use Sewer Connection When:
- Municipal sewer is within reach of the trailer
- Connection cost is justified by the project duration
- High waste volume makes frequent pump-outs impractical
Use a Waste Box When:
- No sewer connection at the site
- Sewer connection is available but cost-prohibitive
- Project is short-term (under 6 months)
- EPA regulations prohibit discharge at the site
- 1 Fresh water tank. Stored inside the insulated, heated box — not in an open tote in the weather.
- 2 Water pump + pressure tank. Built-in 12V pump and pressure tank push water through a heated hose to the trailer. Sinks and toilets work like they are on city water.
- 3 Waste line. The trailer drain runs to the box through a 3-inch line, sloped 1/4 inch per foot, wrapped in heat cable and insulation for winter.
- 4 Sump basin + sewage pump. Waste enters a sump basin inside the box. A sewage pump lifts it through a check valve into the waste tank. High-level alarms warn before anything backs up.
- 5 Waste tank. Sealed and vented inside the box. Out of sight, locked, and above freezing.
- 6 1,000W heater. Electric heater keeps the inside of the box above freezing. Runs on one dedicated 120V / 20A circuit along with the pumps.
- 7 Service ports. Our truck refills water through a 1-inch cam lock fill port and pumps waste through a 2-inch cam lock drain — same side of the box, one visit.
Stahla Water and Waste Equipment
Water Box
- Capacity: 660 gallons, non-potable (dual 330-gal tanks inside an insulated, heated box)
- Pump: Moro DC-10, 12V, ~20 GPM
- Pressure tank: 20 gallons
- Daisy-chain: up to 3 units (1,980 gal total)
- Power: deep-cycle battery, 110V shore charge
- Fill rate: 100 gallons in 10 minutes
- Service: refill 1-2x per week
Waste Box
- Capacity: 660 gallons (dual 330-gal tanks inside an insulated, heated box)
- Pump: dual 1/2-3/4 HP sewage pumps
- Safety: auto-spillover dual sump, high-level alarms
- Daisy-chain: up to 3 units (1,980 gal total)
- Service: pump-out weekly, adjustable
Complete Box
- Capacity: 270 gal fresh + 330 gal waste
- Best for: single trailer, compact sites
- Pumps: 12V water pump with pressure tank; sewage pump with high-level alarms
- Enclosure: insulated, heated (1,000W), lockable
- When needed: single trailer with no water or sewer
Service Frequency
We handle all water refill and waste pump-out service. Frequency is adjusted based on your actual consumption, not a one-size-fits-all schedule.
| Workers | Water Refill | Waste Pump-Out | Notes |
|---|---|---|---|
| 1-4 | Every 2 weeks | Every 2 weeks | Single Water Box sufficient |
| 5-8 | Weekly | Weekly | Single Water Box, single Waste Box |
| 8-12 | 1-2x per week | Weekly | Consider daisy-chaining a second unit |
| 12-20 | 2x per week | 1-2x per week | Daisy-chain 2-3 units, or evaluate city water connection |
EPA Waste Water Compliance
All waste water must be properly contained and disposed of. EPA regulations prohibit discharging gray water or sewage to the ground or storm drains.
- No ground discharge: gray water and sewage must be captured in holding tanks
- Licensed hauler: waste water must be pumped and transported by a licensed waste hauler
- Documentation: maintain pump-out records for environmental compliance audits
Frequently Asked Questions
Need Water and Waste Equipment?
Tell us your crew size and site conditions. We will recommend the right Water Box, Waste Box, or Complete Box package.