Tiny House Water Storage Tanks

Water storage is one of the most critical systems in a tiny house, especially for those seeking mobility or off-grid living. Choosing the right water storage solution can mean the difference between comfort and constant inconvenience. This comprehensive guide will walk you through everything you need to know about tiny house water storage tanks, from selection to installation and maintenance.

1. Understanding Your Tiny House Water Needs

Before selecting a water tank, it’s essential to understand your daily water requirements. The average person uses 80-100 gallons of water per day in a conventional home, but tiny house dwellers typically reduce this significantly.

For a tiny house, consider:
– Drinking and cooking: 2-5 gallons per person daily
– Showering: 5-15 gallons per shower (with water-saving fixtures)
– Toilet flushing: 1-3 gallons per flush (depending on toilet type)
– Dishwashing: 3-5 gallons per day
– Laundry: 15-30 gallons per load (if applicable)

A family of two in a tiny house might reasonably use 20-40 gallons daily with conservation practices in place.

2. Types of Water Storage Tanks for Tiny Houses

Several types of tanks work well for tiny homes:

RV Water Tanks

These are popular choices for tiny houses on wheels. They typically hold 20-100 gallons and are designed for mobile applications. Many tiny house owners opt for RV tanks with a capacity of about 60 gallons, which provides enough water for 2-3 days of conservative use.

Polyethylene Tanks

These durable plastic tanks come in various sizes and are food-grade safe. They’re lightweight, affordable, and resistant to cracking. These are commonly used for both freshwater and greywater storage.

Stainless Steel Tanks

More expensive but extremely durable and sanitary. They don’t impart any taste to the water and are resistant to bacteria growth. These are ideal for drinking water storage.

Bladder Tanks

Flexible tanks that can conform to irregular spaces. When empty, they can be folded and stored, making them excellent for occasional use or as backup systems.

3. Sizing Your Water Tank

For a tiny house, tank size depends on:
– Number of occupants
– Length of time between refills
– Available space
– Water usage habits
– Weight considerations (for tiny houses on wheels)

A common starting point is:
– Solo dweller: 40-60 gallon tank
– Couple: 60-100 gallon tank
– Family: 100+ gallon tank

For off-grid properties, larger external tanks (500-1500 gallons) can be practical alternatives to digging a well, especially if you’re in an area with reliable water delivery services or good rainfall for collection.

4. Tank Placement Considerations

Where you place your water tank affects your entire plumbing system:

Under the Tiny House

Many tiny houses on foundations place tanks underneath the structure. This saves interior space but requires pumps to move water up into the home.

Inside Storage Compartments

Tanks can be placed in dedicated compartments, often under benches, stairs, or in utility closets. This protects them from freezing but takes up valuable space.

Exterior Storage

For off-grid properties, large external tanks can be placed on the ground or partially buried. These must be insulated in cold climates to prevent freezing.

Weight Distribution

For tiny houses on wheels, tank placement significantly affects towing stability. Water weighs approximately 8.3 pounds per gallon, so a full 60-gallon tank adds nearly 500 pounds. Balance this weight over the trailer axles when possible.

5. Plumbing Connections for Water Tanks

Connecting your water tank to your tiny house plumbing system requires several components:

Inlet Connections

– City water hookup: Standard garden hose connection
– Pump fill: Connection for manually filling from external sources
– Rainwater input: Filtered connection from gutters (if applicable)

Outlet Connections

– Water pump: 12V RV-style pump or 120V residential pump
– Pressure regulator: Protects plumbing from excessive pressure
– Filtration system: To ensure water potability
– Distribution manifold: Routes water to different fixtures

Venting

Proper tank venting prevents vacuum lock and allows smooth water flow.

6. Greywater and Blackwater Management

Water storage isn’t just about fresh water—you also need solutions for used water:

Greywater Systems

Greywater from sinks, showers, and washing machines can be:
– Collected in dedicated holding tanks (typically 30-60 gallons)
– Drained directly (where permitted)
– Filtered and reused for irrigation
– Processed through simple filtration for limited reuse

Blackwater Systems

Toilet waste requires special handling:
– Composting toilets eliminate the need for black water storage
– Traditional flush toilets require holding tanks (typically 20-40 gallons)
– Holding tanks need regular pumping service
– Incinerating toilets burn waste, eliminating storage needs

For portable tiny homes on property without sewer connections, many owners opt for composting toilets to eliminate black water entirely, while using a smaller holding tank just for greywater.

7. Winterizing Your Water System

Preventing frozen pipes and tanks is crucial for tiny houses in cold climates:

Insulation Options

– Tank heaters or heating pads
– Insulated tank enclosures
– Heat tape on pipes
– Strategic placement in heated areas

Draining Procedures

For periods of non-use in freezing temperatures:
– Drain all tanks completely
– Use RV antifreeze in p-traps and toilets
– Disconnect and store external hoses
– Blow out lines with compressed air

8. Off-Grid Considerations for Larger Water Storage

For those considering larger external tanks (500-1500 gallons) as alternatives to wells:

Practicality Factors

– Initial cost: $500-2,000 for the tank plus installation
– Delivery fees: $100-300 per water delivery
– Frequency of refills: Typically every 1-3 months for a couple
– Land requirements: Level pad, accessibility for delivery trucks
– Seasonal concerns: Freezing in winter, algae growth in summer

Large tanks can be an excellent alternative to wells, which can cost $5,000-$15,000 to drill. However, the long-term cost of water delivery should be calculated against the one-time cost of a well.

9. Water Conservation Strategies

Maximizing your water storage capacity through conservation:

– Low-flow fixtures can reduce water usage by 30-50%
– Navy showers (turning water off while soaping) save 10-15 gallons per shower
– Dishwashing in basins rather than running water saves 5-10 gallons daily
– Greywater reuse for toilet flushing can save 1-3 gallons per flush
– Rainwater collection can supplement your primary water source

10. Maintenance and Sanitization

Regular maintenance ensures clean, safe water:

– Freshwater tanks should be sanitized with diluted bleach solution (1/4 cup per 15 gallons) every 3-6 months
– Filters require replacement according to manufacturer specifications (typically every 3-12 months)
– Inspect connections and hoses for leaks monthly
– Test water quality quarterly if using rainwater or well water
– Clean gutters and pre-filters monthly if using rainwater collection

Conclusion: Finding Your Perfect Water Storage Solution

The ideal water storage system for your tiny house depends on your specific lifestyle, location, and needs. Mobile tiny houses generally benefit from built-in RV-style systems with moderate capacity (40-100 gallons), while stationary tiny homes might combine smaller interior tanks with larger external storage.

For off-grid properties, large external tanks of 500-1500 gallons can provide months of autonomy, especially when combined with rainwater harvesting and conservation practices. These can be more cost-effective than well-drilling in many situations.

Whatever system you choose, proper planning for your water needs, climate considerations, and maintenance requirements will ensure your tiny house water system provides reliable service for years to come.