Page Contents
- 1 What is PVC?
- 2 Is PVC safe?
- 3 Is PVC approved for potable water?
- 4 Is PVC safe for hydroponic nutrients?
- 5 What are the pros of using PVC?
- 6 What are the cons of using PVC?
- 7 What are alternatives to PVC pipe?
- 8 Conclusion
- 9 Frequently Asked Questions
- 9.1 Can I use just any PVC pipe for hydroponics?
- 9.2 What schedule PVC pipe should I use?
- 9.3 Is CPVC better than PVC?
- 9.4 Can PVC pipe handle hot nutrient water? While CPVC is rated for hot water, schedule 40 PVC starts to deform above 140°F (60°C). Most nutrient solutions are fine at ambient temperatures. If heating your reservoir, keep temperatures under 130°F (55°C). Insulate hot lines as temperature extremes can make PVC brittle. Can PVC pipe withstand UV light?
- 9.5 Is flexible PVC tubing safe?
What is PVC?
PVC stands for polyvinyl chloride, which is a widely used plastic polymer. It’s made by polymerizing vinyl chloride monomers into long chains. PVC is popular because it’s durable, lightweight, low cost, and easy to manufacture into a variety of shapes.
Some key facts about PVC:
- PVC was first created in 1872 but wasn’t mass produced until the 1920s.
- It’s now the 3rd most widely produced plastic in the world after polyethylene and polypropylene.
- PVC can be rigid or flexible depending on the amount of plasticizers added during manufacturing.
- Common uses include pipes, window frames, flooring, bottles, packaging, and more.
PVC is popular for DIY projects and construction because it’s easy to cut, glue, and work with. This makes PVC pipe and fittings an affordable option for building hydroponic systems at home. But is it safe for growing food?
Is PVC safe?
Whether PVC is safe or not has been debated for years. Some key concerns around PVC safety include:
Contains toxic chemicals
PVC contains vinyl chloride, which is a known human carcinogen. Traces of vinyl chloride monomer can potentially leach out of PVC products. Other toxic chemicals like phthalates are also sometimes added to PVC as plasticizers.
However, today’s manufacturing standards have drastically reduced the amounts of harmful residual vinyl chloride and phthalates in most PVC products.
Can leach chemicals
There is disagreement on whether additives and plasticizers in PVC pipe can leach into water over time, especially with exposure to heat and UV light. This depends on the specific PVC formula.
One study found that PVC pipes did not leach concerning levels of plasticizers or BPA into drinking water when tested under standard conditions.
Contains lead
Some PVC products made before the 1978 U.S. Consumer Product Safety Commission reformulation contain lead and cadmium as stabilizer chemicals. This is only an issue with older pipes. Modern PVC approved for potable water should not contain lead.
Off-gassing
PVC can off-gas volatile organic compounds (VOCs) like ethylene dichloride and vinyl chloride, especially when heated. However, studies show off-gassing levels are very low and don’t typically accumulate to dangerous concentrations.
Proper ventilation can prevent buildup of VOCs from PVC inside grow tents or greenhouses.
Produces dioxins when burned
PVC should not be burned, as it can produce toxic dioxins and furans. But this isn’t a concern for PVC pipe used in hydroponics systems.
Not biodegradable
PVC does not biodegrade, so it persists in the environment. This means PVC pipe should be disposed of properly at the end of its useful life.
Overall, while PVC is not without risks, modern food-grade PVC pipe made after 1978 should not contain hazardous chemicals that can leach into hydroponic systems at dangerous levels.
Is PVC approved for potable water?
PVC pipe has been used for municipal water delivery for decades. In the US, PVC pipe must meet standards set by NSF International to come in contact with drinking water. NSF/ANSI Standard 61 certifies PVC pipe as safe for potable water.
PVC water pipes have replaced metal piping in most modern buildings. The convenience and cost savings have made PVC the preferred choice over galvanized steel or copper.
So PVC pipe that meets food-grade specifications should also be fine for hydroponic water lines.
Is PVC safe for hydroponic nutrients?
Hydroponic nutrient solutions have higher salt levels than drinking water. One potential issue is that chloride ions in hydroponic fertilizer may accelerate leaching of chemicals from the PVC material over time.
However, research indicates leaching is minimal and PVC can safely withstand relatively high salt concentrations.
One study tested PVC mini-columns subjected to the equivalent of 20 years exposure to hydroponic nutrient solution. Researchers analyzed 141 potential migrants but did not detect any. They concluded PVC was highly stable and suitable for hydroponics.
Another study showed PVC performed better than HDPE plastic when tested with hydroponic nutrient solution at high temperature (158°F/70°C) for 30 days. PVC showed no visual deterioration and minimal leaching.
Provided good quality, food-grade PVC pipe is used, it seems to be compatible with hydroponic fertilizers. Be sure to purchase PVC components approved for potable water using NSF/ANSI 61 standards.
What are the pros of using PVC?
Here are some of the benefits that make PVC a popular choice:
- Low cost – PVC is one of the most affordable piping materials.
- Durable – PVC has good impact resistance and strength. It holds up well to weather and corrosion.
- Versatile – PVC can be used for pipes, fittings, tubing, and more. It’s easy to find PVC components.
- Easy to work with – PVC is lightweight and can be cut, glued, drilled, and assembled with basic tools.
- Food safe – Unplasticized PVC is considered safe for contact with edibles when manufactured properly.
The low cost and DIY-friendly nature of PVC makes it accessible for home hydroponic systems. PVC’s durability and corrosion resistance also lends well to the damp environment of hydroponics.
What are the cons of using PVC?
The main drawbacks and concerns around using PVC for hydroponics include:
- Not biodegradable – PVC breaks down very slowly and accumulates in the environment.
- Leaching concerns – Potential for chemicals to leach out over time, especially with heat or UV exposure.
- Off-gassing – Can release VOCs when heated, but unlikely at dangerous levels when ventilation is provided.
- Brittle when cold – PVC becomes brittle below -10°F (-23°C) so may crack in very cold weather.
- Not reusable – PVC tends to become brittle after exposure to sun and weather, so has limited reuse potential if dismantling a system.
These cons of PVC can influence the decision for hydroponic hobbyists striving for the most sustainable and non-toxic system possible.
What are alternatives to PVC pipe?
Here are some alternate piping options to consider for hydroponics instead of PVC:
HDPE – High-density polyethylene
- Food safe, non-toxic, non-leaching.
- Withstands high temperatures and UV exposure.
- Flexible black tubing easily integrates into hydroponic systems.
- More expensive but longer-lasting than PVC.
ABS – Acrylonitrile butadiene styrene
- Durable plastic commonly used for plumbing.
- Easy to solvent weld together.
- Can withstand higher temperatures than PVC.
- Subject to UV damage with outdoor exposure.
PEX – Cross-linked polyethylene
- Flexible tubing won’t crack like rigid PVC.
- More expensive than PVC but non-toxic and recyclable.
- Requires specialized connections instead of glue.
- Not suitable for outdoor use due to UV degradation.
Polypropylene
- Resistant to weather and UV light.
- Food safe and non-toxic.
- Relatively affordable but not as cheap as PVC.
- Can withstand high temperatures.
Stainless steel
- Reusable, extremely durable.
- Easy to clean and sterilize.
- Resistant to chemicals and weather.
- Heavy and very expensive compared to other options.
Many plastics like HDPE, polypropylene, and PEX pose less health risks compared to PVC. Stainless steel is ideal for food contact and environmental health but comes at a much higher price.
Conclusion
While PVC has some drawbacks when it comes to sustainability and potential leaching, food-grade PVC pipe still appears to be generally safe for use in home hydroponic systems based on current research.
The tiny exposure to chemicals from PVC is likely outweighed by the health benefits of home-grown hydroponic produce. Using good ventilation, UV-blocking paints, and minimizing heat buildup can also help mitigate potential PVC risks.
Overall, PVC seems to remain a smart choice for DIY hydroponics when certified for potable water use. But eco-conscious growers may still prefer plastics like HDPE that are more reusable, UV-stable, and environmentally friendly.
Frequently Asked Questions
Can I use just any PVC pipe for hydroponics?
No, you want to use PVC pipe that is NSF/ANSI 61 certified for potable water. This guarantees it’s formulated without lead or toxic chemicals that could leach into crops. Avoid using random PVC pipes not intended for drinking water.
What schedule PVC pipe should I use?
Schedule 40 or Schedule 80 PVC are suitable thicknesses to withstand typical hydroponic water pressure. Schedule 40 is cheaper and more commonly available. Schedule 80 is thicker but not necessary unless your system will have high pressure.
Is CPVC better than PVC?
CPVC (chlorinated PVC) has higher heat resistance but lower impact resistance. It’s more expensive than PVC without significant benefits for low-pressure hydroponic systems. Stick with standard PVC unless you need to withstand very high temperatures.