An Andy Gump is a portable toilet without a holding tank
An Andy Gump is a portable restroom that has no underground holding tank or septic connection. Instead of storing waste below ground, it sits above the surface with a visible waste tank underneath or built into the unit itself. The toilet flushes into that tank, which must be emptied by a service truck when full — the same way a standard portable toilet works, except the tank is part of the unit rather than buried.
The name comes from the comic strip character Andy Gump, though the origin of why this particular toilet design carries that name is unclear. What matters is that if you see "Andy Gump" in a rental catalog or contract, you are looking at a self-contained portable restroom, not a unit connected to permanent plumbing or a septic system.
Andy Gumps are common at construction sites, outdoor events, and temporary locations where digging a pit or running sewer lines is not practical or cost-effective. They are also used in places where the ground is too hard, too wet, or too contaminated to install traditional septic infrastructure.
Key Takeaways
- An Andy Gump is a portable toilet with a waste tank built into or attached to the unit, requiring regular pumping but no underground installation.
- The tank sits above ground and is emptied by a service vehicle, making it faster to install and remove than units requiring excavation.
- Andy Gumps cost less upfront than installing temporary septic systems but require scheduled service visits to prevent overflow.
- They work in locations where digging is impossible, dangerous, or prohibited, such as rocky terrain, flood zones, or contaminated sites.
How the tank and flushing system work
When you flush an Andy Gump toilet, waste and water flow down into the holding tank below or beside the seat. The tank is sealed and sits on the ground surface, usually made of plastic or fiberglass. A vent pipe runs from the tank to the roof of the unit to prevent pressure buildup and reduce odor.
The tank has a capacity that varies by model — typically 40 to 100 gallons for a single-stall unit. As the tank fills, the level rises. When it reaches capacity or near capacity, the rental company sends a service truck to pump it out. The truck connects a hose to a valve on the tank, creates suction, and pulls the waste into the truck's holding tank for transport to a treatment facility.
Some Andy Gumps have a straightforward gravity-fed flush system that uses water stored in a tank above the seat. Others have a foot pump or hand pump to create flushing pressure. A few newer models include a small electric pump powered by a battery or solar panel. The flushing mechanism itself is separate from the waste tank — it straightforward provides the water to move waste downward.
Differences between Andy Gumps and standard portable toilets
A standard portable toilet (sometimes called a port-a-potty) also has a holding tank and requires pumping. The main difference is installation: a standard portable toilet is a complete, self-contained unit that arrives on a truck and sits on the ground with no setup required. An Andy Gump is also self-contained, but the term usually refers to older or simpler designs where the tank is more visible or the unit is more basic in construction.
In practice, the terms are often used interchangeably. Both have above-ground tanks, both require regular service, and both work in temporary locations. The distinction matters mainly when comparing costs or features — an Andy Gump rental may be cheaper because it lacks some of the amenities of a newer portable toilet, such as a hand sanitizer dispenser, interior lighting, or a ventilation fan.
Andy Gumps differ from vault toilets, which are permanent structures with a large underground pit that does not require pumping as often. They also differ from composting toilets, which break down waste without water or chemicals, and from incinerating toilets, which burn waste to ash.
When an Andy Gump is the right choice
An Andy Gump works well when you need a toilet in a location where digging is not possible. Rocky ground, shallow bedrock, high water tables, and contaminated soil all make underground tanks impractical. If the site is temporary — a construction project lasting weeks or months, an outdoor event, or a film set — the cost and time to install permanent plumbing make a portable option more sensible.
They are also used in places where environmental regulations prohibit underground waste storage. Wetlands, floodplains, and areas near drinking water sources often have rules against septic systems. A portable toilet can be removed entirely when the project ends, leaving no trace.
Cost is another factor. Renting an Andy Gump for three months costs far less than installing a temporary septic system, which requires excavation, permits, and professional installation. If you need only one or two toilets for a short period, a portable unit is almost always cheaper than any ground-based alternative.
Service and maintenance requirements
An Andy Gump requires regular pumping — typically every one to two weeks, depending on how many people use it and how often. The rental company schedules service visits based on the tank capacity and expected usage. If the tank fills before the scheduled service date, you must call for an emergency pump-out, which usually costs more than a regular service visit.
Between service visits, the unit needs basic maintenance. Keep the toilet seat clean, do not flush anything except human waste and toilet paper, and report any leaks or damage to the rental company when ready. Some units have a water tank that must be refilled — the service technician usually does this during each visit, but you may need to refill it if usage is heavier than expected.
The rental company is responsible for major repairs and replacement parts. If the flush mechanism breaks, the vent pipe cracks, or the tank develops a leak, contact your rental provider. Do not attempt repairs yourself, as improper work can create health and environmental hazards.
Cost factors for Andy Gump rentals
The cost of renting an Andy Gump depends on several factors: how long you need it, how often it will be serviced, how many units you rent, and your location. A single unit for one month typically costs between $75 and $150 per month in most areas, though prices vary widely by region and rental company.
Service visits are usually included in the rental price if scheduled in advance. Emergency pump-outs, after-hours service, or additional visits beyond the standard schedule cost extra. Some rental companies charge a delivery and pickup fee, while others include it in the monthly rate. Always ask what is included in the quoted price before signing a contract.
If you need multiple units or a long-term rental (six months or more), many companies offer discounts. Seasonal demand also affects price — summer months and event season are typically more expensive than winter.
Frequently Asked Questions
How often does an Andy Gump need to be pumped out?
Most Andy Gumps are serviced every one to two weeks, though the exact schedule depends on tank size and how many people use it daily. A rental company will recommend a service frequency based on your expected usage and adjust it if the tank fills faster or slower than anticipated.
Can I install an Andy Gump myself, or does it require a professional?
Delivery and placement are handled by the rental company — they bring the unit on a truck and position it where you need it. You do not install it yourself. The company also handles all pumping and maintenance. Your only responsibility is to use it properly and report problems.
What happens if the tank overflows?
If the tank fills completely and is not pumped, it will overflow, creating a health and environmental hazard. This is why regular service is essential. If you think the tank is getting full before the scheduled service date, call the rental company for an emergency pump-out rather than waiting.
Is an Andy Gump the same as a port-a-potty?
The terms are often used interchangeably. Both are portable toilets with above-ground holding tanks that require regular pumping. "Andy Gump" usually refers to simpler or older designs, while "port-a-potty" is a broader term that includes many types of portable restrooms. The function and service requirements are essentially the same.
Can I use an Andy Gump in winter?
Yes, but cold weather can slow bacterial breakdown and make pumping more difficult if the waste freezes. Rental companies in cold climates use additives and heated tanks to prevent freezing. Let your rental provider know if you need winter service so they can prepare the unit appropriately.