February 23, 2019

Water Storage by Art Ludwig

The Big Idea: For small volumes of water storage, use ferrocement if you can and plastic if you cannot. For large volumes of water storage, use ponds if you can and ferrocement if you cannot.

Design Principles

1. Lease as much of the water work as possible to nature.
2. Divert water just after evaporation or soil has naturally purified it.
3. Divert water higher than the point of storage and points of use.
4. Conserve pressure in the plumbing.
5. Use adequately, but not excessively, sized pipe.
6. Design to extract benefit from other attributes of your water.
7. Rigorously confine materials that are incompatible with natural cycles. 
8. Intervene as little as possible.
9. Use appropriate technology.
10. Practice moderate and efficient resource use. Context is everything.

Book Notes

  • Going from 99% water availability to 99.5% doubles the financial and environmental cost.
  • People in industrialized society with running water use about 100 gallons a day. People who have to carry water use about 10 gallons a day.
  • Well-designed water storage can actually increase water quality over time. 
  • Poorly designed water storage can have many problems: algae growth, bacteria, leaks, sediment buildup, leached carcinogens.
  • Try to avoid chlorine to disinfect drinking water as there are carcinogenic byproducts.
  • UV light is an ideal disinfectant.
  • Nothing beats commercial water quality tests, but you can do dome DIY testing for turbidity, flow, dissolved solids, elevation, general bacteria, and fecal coliform bacteria. 
  • 5 ways to store water: none (direct from natural water source), store in soil, store in aquifers, store in ponds, store in tanks. 
  • Store in soil: divert water to be soaked up by the soil, where it can be absorbed by plant roots.
  • How to increase the amount of water in your aquifer: take out less water, slow down rainwater runoff, detain water in infiltration basins, infiltrate water through creek beds and riverbeds.
  • Aquifers recharge naturally through rainwater, but over drafting groundwater can lead to drafting fossil groundwater that has been stored for millions of years. 
  • Chemicals and toxins seep into the soil and contaminate groundwater. 
  • Storing water in ponds is cheap but open to contamination and exposed to evaporation.
  • Three types of man-made ponds: storage ponds, living ponds, runoff harvesting ponds.
  • Water tanks are the most common way to store water. 
  • To increase water pressure, put the tank on a hill, make a water tower, use a small pressure tank, put a tank on your roof.
  • With your tank at roof height, your appliances will barely work. With your tank 10 stories high, your washing machine, water purifier, and water heater will start to work.
  • You can install a booster pump just for fire safety. 
  • Tubs and kitchen need flow, not high water pressure. 
  • Burying water storage tanks can have some advantages but also many disadvantages. 
  • If harvesting rainwater, carefully calculate usage (output) and rainfall (input) to size your water tank.
  • The classic tank shape (cylindrical, height = diameter) is usually the way to go.
  • Ferrocement tanks are a great option for tank construction for a permanent tank.
  • HDPE is the preferred plastic for water tank.
  • EPDM is the best artificial pond liner.
  • Galvanized steel with plastic membrane is a newer but promising technology.
  • Food-grade IBC totes can also be used for small water tanks.
  • A plastic tank, then encased in masonry for shade and protection is a high-performance, lifetime tank.
  • The earth under the tank should be compacted and free of rocks. Drainage should be away from the tank. 
  • For small volumes, DIY ferrocement and plastic tanks are the most cost-effective. For large volumes, ponds are the most cost-effective. 
  • A pressure tank provides water pressure but requires continuous power. Larger pressure tanks can provide more reserves.
  • Be sure to critter-proof the tank from mosquitoes, rodents, and other critters. 
  • Keep out the sun to prevent algae. Metal and masonry completely block out light. 
  • Paint your tank white to reflect sunlight and keep the tank cooler. 
  • Take measures (insulation, south-facing, partial-burying) to keep the tank from freezing in the winter.
  • To protect your agricultural land against fires, use fire-safe landscaping, occasional managed fires, robust water systems, fire-proof building materials like metal and concrete