Just purchased a new 2017 (dealer made a deal i couldn't pass up to more it off the lot) Redwood 3901WB model and there is low water pressure when connected at parks. Though maybe it was the park pressure but just connected at home which has great pressure and no real improvement. Though maybe inline water filter bad - opened it and it appears to be good an clean. Will they go bad from just sitting without water flow? Trailer was on dealers lot for 18 months or so. No open drains leaking anywhere. Shower head does not work well due to lack of pressure. Using same hose and pressure regulator i used on the last trailer which had no issues with pressure.

Any ideas on why I might not have good pressure?

If you're using one of these, try without it, unless you have 100 psi+ at your house faucet. These types of so called regulators restrict the flow to reduce the pressure.
Try with the onboard pump from the fresh water tank, if still very weak you may have kinked line somewhere.
Replace the POS factory shower head with an Oxygenics!
Before using this new rv too much I'd be sanitizing the water lines & fresh water tank, replace the onboard filter cartridge, rinse the water heater thoroughly, it's been sitting around for a year & half, who knows how long water has been in it.

What happens with the pressure throughout if you fill the fresh water tank with water and run the water pump?

x

I removed my in-house inline filter cartridge and that increased my pressure. I also removed all the screens that are on the ends of the faucets and cleaned them of debris. I took the shower head off and removed the water regulator that is built into the shower head ( small black plastic )...

My pressure is better now

Thanks everyone.

- I did clean the shower head. One of the small three holes was plugged and that made it better. Also checked all the other faucet filter ends.
- I will try without the pressure regulator on it.
- I do plan on flushing everything good
- will take that little water regulator out of the shower head also or I may just go by a better one like you said.

Thanks all.

Anyone know what filter number I need to replace the inline filter. I has the all blue, not clear, outer shell and is 10" long. Only markings on it Pentek on the outer shell and the number 292 on the filter end itself. Can't find anything online that matches.

Removed the inline pressure regulator (type you show here) and wow what a difference. I have around 70 lbs of pressure at the house. Don't like not having some regulator so I just ordered an adjustable one that does not reduce flow which many comments indicate is the case. go flow even when regulated down to under 50 lbs of pressure. Will let you know how things are once I get it and try it out.

Removed the inline pressure regulator (type you show here) and wow what a difference. I have around 70 lbs of pressure at the house. Don't like not having some regulator so I just ordered an adjustable one that does not reduce flow which many comments indicate is the case. go flow even when regulated down to under 50 lbs of pressure. Will let you know how things are once I get it and try it out.

My adjustable regulator came preset at 55 psi which is good pressure if the faucet your connected to is that high.
The 10" filter cartridge is a very common replacement at Wal-Mart or HD/Lowes. I usually get the 2 pack at Wal-Mart for about $10-12. They have ones for sediment or charcoal for improved taste.

I replaced my coach water filter with this one I found on Amazon. There are lots of cartridge choices though for this Pentek filter housing.

https://www.amazon.com/Pentek-ChlorPlus-Carbon-Filter-Cartridge/dp/B07FN661JS/ref=sr_1_1?ie=UTF8&qid=1537893478&sr=8-1&keywords=Pentek+ChlorPlus+10+Carbon+Block+Filter+Cartridge%2C+10%22+x+2-1%2F2%22%2C+1+Micron

x

Thanks everyone. I replaced the straight flow restricting style regulator and replaced it with an adjustable one with the pressure gauge on it and all is good now.